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Page 1
Q u e s t i o n : 1
Find the simple interest and the amount when:
Principal = Rs 6400, rate = 6% p.a. and time = 2 years
S o l u t i o n :
P = Rs. 6400, R = 6%, T = 2 years
S. I. =
P×R×T
100
=
6400×6×2
100
= Rs. 768
Amount=P+S.I.
=6400+768 = Rs. 7168
Q u e s t i o n : 2
Find the simple interest and the amount when:
Principal = Rs 2650, rate = 8% p.a. and time = 2
1
2
years
S o l u t i o n :
P = Rs. 2650, R = 8%, T=2
1
2
years =
5
2
years
S.I. =
P×R×T
100
=
2650×8×5
100×2
= Rs. 530
Amount = P +S. I.
=2650+530 = Rs. 3180
Q u e s t i o n : 3
Find the simple interest and the amount when:
Principal = Rs 1500, rate = 12% p.a. and time = 3 years 3 months.
S o l u t i o n :
P = Rs. 1500, R = 12%, T = 3 +
3
12
=
13
4
years
S.I. =
P×R×T
100
=
1500×12×13
100×4
= Rs. 585
Amount=P+S.I.
=1500+585 =Rs . 2085
Q u e s t i o n : 4
Find the simple interest and the amount when:
Principal = Rs 9600, rate = 7
1
2
%
p.a. and time = 5 months.
S o l u t i o n :
P = Rs. 9600R = 7
1
2
% T = 5 months =
5
12
yearsS. I. =
P×R×T
100
=
9600×15×5
100×2×12
= Rs. 300Amount = P + S. I. = 9600 +300 = Rs. 9900
Q u e s t i o n : 5
Find the simple interest and the amount when:
Principal = Rs 5000, rate = 9% p.a. and time = 146 days.
S o l u t i o n :
P = Rs. 5000 , R = 9% , T = 146 days =
146
365
years
S .I . =
P×R×T
100
=
5000×9×146
100×365
=Rs. 180
Amount=P+S .I .
=5000+180 =Rs . 5180
Q u e s t i o n : 6
Find the time when:
Principal = Rs 6400, SI = Rs 1152 and rate = 6% p.a.
S o l u t i o n :
P = Rs. 6400, S. I. = Rs. 1152, R = 6%
T =
S.I.×100
P×R
=
1152×100
6400×6
=
1152
384
= 3 years
Q u e s t i o n : 7
Find the time when:
Principal = Rs 9540, SI = Rs 1908 and rate = 8% p.a.
S o l u t i o n :
P = Rs. 9540 , S. I. = Rs. 1908, R = 8%
T =
S.I.×100
P×R
=
1908×100
9540×8
=
10
4
=2
1
2
years
Page 2
Q u e s t i o n : 1
Find the simple interest and the amount when:
Principal = Rs 6400, rate = 6% p.a. and time = 2 years
S o l u t i o n :
P = Rs. 6400, R = 6%, T = 2 years
S. I. =
P×R×T
100
=
6400×6×2
100
= Rs. 768
Amount=P+S.I.
=6400+768 = Rs. 7168
Q u e s t i o n : 2
Find the simple interest and the amount when:
Principal = Rs 2650, rate = 8% p.a. and time = 2
1
2
years
S o l u t i o n :
P = Rs. 2650, R = 8%, T=2
1
2
years =
5
2
years
S.I. =
P×R×T
100
=
2650×8×5
100×2
= Rs. 530
Amount = P +S. I.
=2650+530 = Rs. 3180
Q u e s t i o n : 3
Find the simple interest and the amount when:
Principal = Rs 1500, rate = 12% p.a. and time = 3 years 3 months.
S o l u t i o n :
P = Rs. 1500, R = 12%, T = 3 +
3
12
=
13
4
years
S.I. =
P×R×T
100
=
1500×12×13
100×4
= Rs. 585
Amount=P+S.I.
=1500+585 =Rs . 2085
Q u e s t i o n : 4
Find the simple interest and the amount when:
Principal = Rs 9600, rate = 7
1
2
%
p.a. and time = 5 months.
S o l u t i o n :
P = Rs. 9600R = 7
1
2
% T = 5 months =
5
12
yearsS. I. =
P×R×T
100
=
9600×15×5
100×2×12
= Rs. 300Amount = P + S. I. = 9600 +300 = Rs. 9900
Q u e s t i o n : 5
Find the simple interest and the amount when:
Principal = Rs 5000, rate = 9% p.a. and time = 146 days.
S o l u t i o n :
P = Rs. 5000 , R = 9% , T = 146 days =
146
365
years
S .I . =
P×R×T
100
=
5000×9×146
100×365
=Rs. 180
Amount=P+S .I .
=5000+180 =Rs . 5180
Q u e s t i o n : 6
Find the time when:
Principal = Rs 6400, SI = Rs 1152 and rate = 6% p.a.
S o l u t i o n :
P = Rs. 6400, S. I. = Rs. 1152, R = 6%
T =
S.I.×100
P×R
=
1152×100
6400×6
=
1152
384
= 3 years
Q u e s t i o n : 7
Find the time when:
Principal = Rs 9540, SI = Rs 1908 and rate = 8% p.a.
S o l u t i o n :
P = Rs. 9540 , S. I. = Rs. 1908, R = 8%
T =
S.I.×100
P×R
=
1908×100
9540×8
=
10
4
=2
1
2
years
Q u e s t i o n : 8
Find the time when:
Principal = Rs 5000, amount = Rs 6450 and rate = 12% p.a.
S o l u t i o n :
P = Rs. 5000, A=Rs. 6450, R = 12%
S. I. = A -P
= 6450 -5000
= Rs. 1450
T =
S.I×100
P×R
=
1450×100
5000×12
=
29
12
= 2
5
12
=2 years 5 months
Q u e s t i o n : 9
Find the rate when:
Principal = Rs 8250, SI = Rs 1100 and time = 2 years.
S o l u t i o n :
P = Rs. 8250, S. I. = Rs. 1100, T = 2 years
R=
S.I.×100
P×T
=
1100×100
8250×2
=
1100
165
=6.67%
Q u e s t i o n : 1 0
Find the rate when:
Principal = Rs 5200, SI = Rs 975 and time = 2
1
2
years.
S o l u t i o n :
P= Rs. 5200 , S.I.=Rs. 975 [ T=2
1
2
years=
5
2
years]
R=
S.I.×100
P×T
=
975×100×2
5200×5
=
195
26
=7.5%
Q u e s t i o n : 1 1
Find the rate when:
Principal = Rs 3560, amount = Rs 4521.20 and time = 3 years.
S o l u t i o n :
P = Rs. 3560 , A = Rs. 4521. 20 , T = 3 years
S. I. = A -P = 4521. 20 -3560
= Rs. 961. 20
R =
S.I.×100
P×T
=
961.20×100
3560×3
=
96120×100
100×3560×3
=9%
Q u e s t i o n : 1 2
Shanta borrowed Rs 6000 from the State Bank of India for 3 years 8 months at 12% per annum. What amount will clear off her debt?
S o l u t i o n :
P = Rs 6000, R = 12%, T=3 years 8 months = 3
8
12
=
44
12
years
S.I. =
P×R×T
100
=
6000×12×44
100×12
= Rs 2640
A = P +S. I.
= 6000 +2640
= Rs 8640
Q u e s t i o n : 1 3
Hari borrowed Rs 12600 from a moneylender at 15% per annum simple interest. After 3 years, he paid Rs 7070 and gave a goat to clear off the debt. What is the cost of the goat?
S o l u t i o n :
P = Rs. 12600 R = 15% T = 3 years
S.I.=
P×R×T
100
=
12600×15×3
100
=Rs. 5670
A = Rs. 12600 +Rs. 5670 = Rs. 18270
Hari had to pay Rs. 18270 to the money lender, but he paid Rs. 7070 and a goat.
? Cost of the goat = Rs. 18270 -Rs. 7070
= Rs. 11200
Q u e s t i o n : 1 4
The simple interest on a certain sum for 3 years at 10% per annum is Rs 829.50. Find the sum.
S o l u t i o n :
Page 3
Q u e s t i o n : 1
Find the simple interest and the amount when:
Principal = Rs 6400, rate = 6% p.a. and time = 2 years
S o l u t i o n :
P = Rs. 6400, R = 6%, T = 2 years
S. I. =
P×R×T
100
=
6400×6×2
100
= Rs. 768
Amount=P+S.I.
=6400+768 = Rs. 7168
Q u e s t i o n : 2
Find the simple interest and the amount when:
Principal = Rs 2650, rate = 8% p.a. and time = 2
1
2
years
S o l u t i o n :
P = Rs. 2650, R = 8%, T=2
1
2
years =
5
2
years
S.I. =
P×R×T
100
=
2650×8×5
100×2
= Rs. 530
Amount = P +S. I.
=2650+530 = Rs. 3180
Q u e s t i o n : 3
Find the simple interest and the amount when:
Principal = Rs 1500, rate = 12% p.a. and time = 3 years 3 months.
S o l u t i o n :
P = Rs. 1500, R = 12%, T = 3 +
3
12
=
13
4
years
S.I. =
P×R×T
100
=
1500×12×13
100×4
= Rs. 585
Amount=P+S.I.
=1500+585 =Rs . 2085
Q u e s t i o n : 4
Find the simple interest and the amount when:
Principal = Rs 9600, rate = 7
1
2
%
p.a. and time = 5 months.
S o l u t i o n :
P = Rs. 9600R = 7
1
2
% T = 5 months =
5
12
yearsS. I. =
P×R×T
100
=
9600×15×5
100×2×12
= Rs. 300Amount = P + S. I. = 9600 +300 = Rs. 9900
Q u e s t i o n : 5
Find the simple interest and the amount when:
Principal = Rs 5000, rate = 9% p.a. and time = 146 days.
S o l u t i o n :
P = Rs. 5000 , R = 9% , T = 146 days =
146
365
years
S .I . =
P×R×T
100
=
5000×9×146
100×365
=Rs. 180
Amount=P+S .I .
=5000+180 =Rs . 5180
Q u e s t i o n : 6
Find the time when:
Principal = Rs 6400, SI = Rs 1152 and rate = 6% p.a.
S o l u t i o n :
P = Rs. 6400, S. I. = Rs. 1152, R = 6%
T =
S.I.×100
P×R
=
1152×100
6400×6
=
1152
384
= 3 years
Q u e s t i o n : 7
Find the time when:
Principal = Rs 9540, SI = Rs 1908 and rate = 8% p.a.
S o l u t i o n :
P = Rs. 9540 , S. I. = Rs. 1908, R = 8%
T =
S.I.×100
P×R
=
1908×100
9540×8
=
10
4
=2
1
2
years
Q u e s t i o n : 8
Find the time when:
Principal = Rs 5000, amount = Rs 6450 and rate = 12% p.a.
S o l u t i o n :
P = Rs. 5000, A=Rs. 6450, R = 12%
S. I. = A -P
= 6450 -5000
= Rs. 1450
T =
S.I×100
P×R
=
1450×100
5000×12
=
29
12
= 2
5
12
=2 years 5 months
Q u e s t i o n : 9
Find the rate when:
Principal = Rs 8250, SI = Rs 1100 and time = 2 years.
S o l u t i o n :
P = Rs. 8250, S. I. = Rs. 1100, T = 2 years
R=
S.I.×100
P×T
=
1100×100
8250×2
=
1100
165
=6.67%
Q u e s t i o n : 1 0
Find the rate when:
Principal = Rs 5200, SI = Rs 975 and time = 2
1
2
years.
S o l u t i o n :
P= Rs. 5200 , S.I.=Rs. 975 [ T=2
1
2
years=
5
2
years]
R=
S.I.×100
P×T
=
975×100×2
5200×5
=
195
26
=7.5%
Q u e s t i o n : 1 1
Find the rate when:
Principal = Rs 3560, amount = Rs 4521.20 and time = 3 years.
S o l u t i o n :
P = Rs. 3560 , A = Rs. 4521. 20 , T = 3 years
S. I. = A -P = 4521. 20 -3560
= Rs. 961. 20
R =
S.I.×100
P×T
=
961.20×100
3560×3
=
96120×100
100×3560×3
=9%
Q u e s t i o n : 1 2
Shanta borrowed Rs 6000 from the State Bank of India for 3 years 8 months at 12% per annum. What amount will clear off her debt?
S o l u t i o n :
P = Rs 6000, R = 12%, T=3 years 8 months = 3
8
12
=
44
12
years
S.I. =
P×R×T
100
=
6000×12×44
100×12
= Rs 2640
A = P +S. I.
= 6000 +2640
= Rs 8640
Q u e s t i o n : 1 3
Hari borrowed Rs 12600 from a moneylender at 15% per annum simple interest. After 3 years, he paid Rs 7070 and gave a goat to clear off the debt. What is the cost of the goat?
S o l u t i o n :
P = Rs. 12600 R = 15% T = 3 years
S.I.=
P×R×T
100
=
12600×15×3
100
=Rs. 5670
A = Rs. 12600 +Rs. 5670 = Rs. 18270
Hari had to pay Rs. 18270 to the money lender, but he paid Rs. 7070 and a goat.
? Cost of the goat = Rs. 18270 -Rs. 7070
= Rs. 11200
Q u e s t i o n : 1 4
The simple interest on a certain sum for 3 years at 10% per annum is Rs 829.50. Find the sum.
S o l u t i o n :
Let the sum be Rs. P.
S.I. = Rs. 829. 50, T = 3 years, R = 10%
Now, P=
S.I×100
R×T
=
829.50×100
10×3
=
8295
3
= 2765Hence, the sum is Rs. 2765.
Q u e s t i o n : 1 5
A sum when reckoned at 7
1
2
%
per annum amounts to Rs 3920 in 3 years. Find the sum
S o l u t i o n :
Let the required sum be Rs. x.
A = Rs. 3920, R = 7
1
2
%, T = 3 years
Now,
Now, S.I.=
P×R×T
100
=
x×15×3
2×100
=
9x
40
A = P +S. I.
= x +
9x
40
=
40x+9x
40
=
49x
40
But the amount is Rs. 3920.
= >
49x
40
= 3920
= > x =
3920×40
49
=
156800
49
= 3200
Hence, the required sum is Rs. 3200.
Q u e s t i o n : 1 6
A sum of money put at 11% per annum amounts to Rs 4491 in 2 years 3 months. What will it amount to in 3 years at the same rate?
S o l u t i o n :
Given: R=11%, T=2 years 3 months = 2+
3
12
=
27
12
years
Let the required sum be Rs. x.
S.I.=
P×R×T
100
=
x×11×27
9
100×12 4
=
99x
400
A = P +S. I.
= x +
99x
400
=
400x+99x
400
=
499x
400
But the amount is Rs. 4491.
= >
499x
400
= 4491
= > x =
4491×400
499
=
1796400
499
= 3600
Hence, the required sum is Rs. 3600.
? S.I.=
P×R×T
100
=
3600×11×3
100
= Rs. 1188
? Amount=P+S.I.=3600+1188
=Rs. 4788
Q u e s t i o n : 1 7
A sum of money invested at 8% per annum amounts to Rs 12122 in 2 years. What will it amount to in 2 years 8 months at 9% per annum?
S o l u t i o n :
Let the required sum be Rs. x.
S.I.=
P×R×T
100
=
x×8×2
100
=
16x
100
A = P +S. I.
= x +
16x
100
=
100x+16x
100
=
116x
100
But the amount is Rs. 12122.
= >
116x
100
= 12122
= > x =
12122×100
116
= 10450
Now, S.I.=
P×R×T
100
=
10450×9
3
×32
8
100×12 4 1 = Rs. 2508
? A=P+S.I.
= Rs. 10450 + Rs. 2508
= Rs. 12958
Q u e s t i o n : 1 8
At what rate per cent per annum will Rs 3600 amount to Rs 4734 in 3
1
2
years?
S o l u t i o n :
P = Rs. 3600 A = Rs. 4734 T= 3
1
2
=
7
2
years
S. I. = A -P
= 4734 -3600
= Rs. 1134
R=
S.I.×100
P×T
=
1134×100×2
3600×7
=9%
Q u e s t i o n : 1 9
If Rs 640 amounts to Rs 768 in 2 years 6 months, what will Rs 850 amount to in 3 years at the same rate per cent per annum?
S o l u t i o n :
Page 4
Q u e s t i o n : 1
Find the simple interest and the amount when:
Principal = Rs 6400, rate = 6% p.a. and time = 2 years
S o l u t i o n :
P = Rs. 6400, R = 6%, T = 2 years
S. I. =
P×R×T
100
=
6400×6×2
100
= Rs. 768
Amount=P+S.I.
=6400+768 = Rs. 7168
Q u e s t i o n : 2
Find the simple interest and the amount when:
Principal = Rs 2650, rate = 8% p.a. and time = 2
1
2
years
S o l u t i o n :
P = Rs. 2650, R = 8%, T=2
1
2
years =
5
2
years
S.I. =
P×R×T
100
=
2650×8×5
100×2
= Rs. 530
Amount = P +S. I.
=2650+530 = Rs. 3180
Q u e s t i o n : 3
Find the simple interest and the amount when:
Principal = Rs 1500, rate = 12% p.a. and time = 3 years 3 months.
S o l u t i o n :
P = Rs. 1500, R = 12%, T = 3 +
3
12
=
13
4
years
S.I. =
P×R×T
100
=
1500×12×13
100×4
= Rs. 585
Amount=P+S.I.
=1500+585 =Rs . 2085
Q u e s t i o n : 4
Find the simple interest and the amount when:
Principal = Rs 9600, rate = 7
1
2
%
p.a. and time = 5 months.
S o l u t i o n :
P = Rs. 9600R = 7
1
2
% T = 5 months =
5
12
yearsS. I. =
P×R×T
100
=
9600×15×5
100×2×12
= Rs. 300Amount = P + S. I. = 9600 +300 = Rs. 9900
Q u e s t i o n : 5
Find the simple interest and the amount when:
Principal = Rs 5000, rate = 9% p.a. and time = 146 days.
S o l u t i o n :
P = Rs. 5000 , R = 9% , T = 146 days =
146
365
years
S .I . =
P×R×T
100
=
5000×9×146
100×365
=Rs. 180
Amount=P+S .I .
=5000+180 =Rs . 5180
Q u e s t i o n : 6
Find the time when:
Principal = Rs 6400, SI = Rs 1152 and rate = 6% p.a.
S o l u t i o n :
P = Rs. 6400, S. I. = Rs. 1152, R = 6%
T =
S.I.×100
P×R
=
1152×100
6400×6
=
1152
384
= 3 years
Q u e s t i o n : 7
Find the time when:
Principal = Rs 9540, SI = Rs 1908 and rate = 8% p.a.
S o l u t i o n :
P = Rs. 9540 , S. I. = Rs. 1908, R = 8%
T =
S.I.×100
P×R
=
1908×100
9540×8
=
10
4
=2
1
2
years
Q u e s t i o n : 8
Find the time when:
Principal = Rs 5000, amount = Rs 6450 and rate = 12% p.a.
S o l u t i o n :
P = Rs. 5000, A=Rs. 6450, R = 12%
S. I. = A -P
= 6450 -5000
= Rs. 1450
T =
S.I×100
P×R
=
1450×100
5000×12
=
29
12
= 2
5
12
=2 years 5 months
Q u e s t i o n : 9
Find the rate when:
Principal = Rs 8250, SI = Rs 1100 and time = 2 years.
S o l u t i o n :
P = Rs. 8250, S. I. = Rs. 1100, T = 2 years
R=
S.I.×100
P×T
=
1100×100
8250×2
=
1100
165
=6.67%
Q u e s t i o n : 1 0
Find the rate when:
Principal = Rs 5200, SI = Rs 975 and time = 2
1
2
years.
S o l u t i o n :
P= Rs. 5200 , S.I.=Rs. 975 [ T=2
1
2
years=
5
2
years]
R=
S.I.×100
P×T
=
975×100×2
5200×5
=
195
26
=7.5%
Q u e s t i o n : 1 1
Find the rate when:
Principal = Rs 3560, amount = Rs 4521.20 and time = 3 years.
S o l u t i o n :
P = Rs. 3560 , A = Rs. 4521. 20 , T = 3 years
S. I. = A -P = 4521. 20 -3560
= Rs. 961. 20
R =
S.I.×100
P×T
=
961.20×100
3560×3
=
96120×100
100×3560×3
=9%
Q u e s t i o n : 1 2
Shanta borrowed Rs 6000 from the State Bank of India for 3 years 8 months at 12% per annum. What amount will clear off her debt?
S o l u t i o n :
P = Rs 6000, R = 12%, T=3 years 8 months = 3
8
12
=
44
12
years
S.I. =
P×R×T
100
=
6000×12×44
100×12
= Rs 2640
A = P +S. I.
= 6000 +2640
= Rs 8640
Q u e s t i o n : 1 3
Hari borrowed Rs 12600 from a moneylender at 15% per annum simple interest. After 3 years, he paid Rs 7070 and gave a goat to clear off the debt. What is the cost of the goat?
S o l u t i o n :
P = Rs. 12600 R = 15% T = 3 years
S.I.=
P×R×T
100
=
12600×15×3
100
=Rs. 5670
A = Rs. 12600 +Rs. 5670 = Rs. 18270
Hari had to pay Rs. 18270 to the money lender, but he paid Rs. 7070 and a goat.
? Cost of the goat = Rs. 18270 -Rs. 7070
= Rs. 11200
Q u e s t i o n : 1 4
The simple interest on a certain sum for 3 years at 10% per annum is Rs 829.50. Find the sum.
S o l u t i o n :
Let the sum be Rs. P.
S.I. = Rs. 829. 50, T = 3 years, R = 10%
Now, P=
S.I×100
R×T
=
829.50×100
10×3
=
8295
3
= 2765Hence, the sum is Rs. 2765.
Q u e s t i o n : 1 5
A sum when reckoned at 7
1
2
%
per annum amounts to Rs 3920 in 3 years. Find the sum
S o l u t i o n :
Let the required sum be Rs. x.
A = Rs. 3920, R = 7
1
2
%, T = 3 years
Now,
Now, S.I.=
P×R×T
100
=
x×15×3
2×100
=
9x
40
A = P +S. I.
= x +
9x
40
=
40x+9x
40
=
49x
40
But the amount is Rs. 3920.
= >
49x
40
= 3920
= > x =
3920×40
49
=
156800
49
= 3200
Hence, the required sum is Rs. 3200.
Q u e s t i o n : 1 6
A sum of money put at 11% per annum amounts to Rs 4491 in 2 years 3 months. What will it amount to in 3 years at the same rate?
S o l u t i o n :
Given: R=11%, T=2 years 3 months = 2+
3
12
=
27
12
years
Let the required sum be Rs. x.
S.I.=
P×R×T
100
=
x×11×27
9
100×12 4
=
99x
400
A = P +S. I.
= x +
99x
400
=
400x+99x
400
=
499x
400
But the amount is Rs. 4491.
= >
499x
400
= 4491
= > x =
4491×400
499
=
1796400
499
= 3600
Hence, the required sum is Rs. 3600.
? S.I.=
P×R×T
100
=
3600×11×3
100
= Rs. 1188
? Amount=P+S.I.=3600+1188
=Rs. 4788
Q u e s t i o n : 1 7
A sum of money invested at 8% per annum amounts to Rs 12122 in 2 years. What will it amount to in 2 years 8 months at 9% per annum?
S o l u t i o n :
Let the required sum be Rs. x.
S.I.=
P×R×T
100
=
x×8×2
100
=
16x
100
A = P +S. I.
= x +
16x
100
=
100x+16x
100
=
116x
100
But the amount is Rs. 12122.
= >
116x
100
= 12122
= > x =
12122×100
116
= 10450
Now, S.I.=
P×R×T
100
=
10450×9
3
×32
8
100×12 4 1 = Rs. 2508
? A=P+S.I.
= Rs. 10450 + Rs. 2508
= Rs. 12958
Q u e s t i o n : 1 8
At what rate per cent per annum will Rs 3600 amount to Rs 4734 in 3
1
2
years?
S o l u t i o n :
P = Rs. 3600 A = Rs. 4734 T= 3
1
2
=
7
2
years
S. I. = A -P
= 4734 -3600
= Rs. 1134
R=
S.I.×100
P×T
=
1134×100×2
3600×7
=9%
Q u e s t i o n : 1 9
If Rs 640 amounts to Rs 768 in 2 years 6 months, what will Rs 850 amount to in 3 years at the same rate per cent per annum?
S o l u t i o n :
P = Rs. 640, A = Rs. 768, T=2 years 6 months =
5
2
years
S. I. = A -P
= 768 -640
= Rs. 128
R=
S.I.×100
P×T
=
128×100×2
640×5
=8%
P = Rs. 850, R = 8%, T = 3 years
? S.I. =
P×R×T
100
=
850×8×3
100
=
2040
10
=Rs. 204
? A = P +S. I.
= 850 +204
= Rs. 1054
Q u e s t i o n : 2 0
In what time will Rs 5600 amount to Rs 6720 at 8% per annum?
S o l u t i o n :
P = Rs. 5600, A = Rs. 6720, R = 8%
S. I. = A -P
= 6720 -5600
= Rs. 1120
T=
S.I.×100
P×R
=
1120×100
5600×8
=
1120
448
=2
1
2
years
Q u e s t i o n : 2 1
A sum of money becomes
8
5
of itself in 5 years at a certain rate of simple interest. Find the rate of interest.
S o l u t i o n :
Let the sum be Rs. x .
Amount=
8x
5
? S.I.=A -P=
8x
5
-x
=
3x
5
Let the rate be R%.
S.I.=
P×R×T
100
= >
3x
5
=
x×R×5
1
100 20
= > 3x ×20 = R ×x ×5
= > R =
3×x×20
4
x×5
= 12
Hence, the rate of interest is 12 %.
Q u e s t i o n : 2 2
A sum of money lent at simple interest amounts to Rs 783 in 2 years and to Rs 837 in 3 years. Find the sum and the rate per cent per annum.
S o l u t i o n :
Amount in 3 years = (Principal + S. I. for 3 years) = Rs. 837
Amount in 2 years = (Principal + S. I. for 2 years) = Rs. 783
On subtracting:
S. I. for 1 year = (837 -783) = Rs. 54
S. I. for 2 years=
54
1
×2 = Rs. 108
? Sum = Amount for 2 years -S. I. for 2 years
= 783 -108
= Rs. 675
P = Rs. 675, S. I. = Rs. 108 and T = 2 years
R =
S.I.×100
P×T
=
108×100
50 2
675 27 ×2 1
= 8%
Q u e s t i o n : 2 3
A sum of money lent at simple interest amount to Rs 4745 in 3 years and to Rs 5475 in 5 years. Find the sum and the rate per cent per annum.
S o l u t i o n :
Amount in 5 years = (Principal + S. I. for 5 years) = Rs. 5475
Amount in 3 years = (Principal + S. I. for 3 years) = Rs. 4745
On subtracting:
S. I. for 2 years = (5475 -4745) = Rs. 730
S. I. for 3 years=
730
2
×3 = Rs. 1095
? Sum = Amount for 3 years -S. I. for 3 years
= 4745 -1095
= Rs. 3650
P=Rs. 3650, S.I.=Rs. 1095, T=3 years
R=
S.I.×100
P×T
=
1095×100
3650×3
= 10%
Q u e s t i o n : 2 4
Divide Rs 3000 into two parts such that the simple interest on the first part for 4 years at 8% per annum is equal to the simple interest on the second part for 2 years at 9% per annum.
S o l u t i o n :
( )
( )
Page 5
Q u e s t i o n : 1
Find the simple interest and the amount when:
Principal = Rs 6400, rate = 6% p.a. and time = 2 years
S o l u t i o n :
P = Rs. 6400, R = 6%, T = 2 years
S. I. =
P×R×T
100
=
6400×6×2
100
= Rs. 768
Amount=P+S.I.
=6400+768 = Rs. 7168
Q u e s t i o n : 2
Find the simple interest and the amount when:
Principal = Rs 2650, rate = 8% p.a. and time = 2
1
2
years
S o l u t i o n :
P = Rs. 2650, R = 8%, T=2
1
2
years =
5
2
years
S.I. =
P×R×T
100
=
2650×8×5
100×2
= Rs. 530
Amount = P +S. I.
=2650+530 = Rs. 3180
Q u e s t i o n : 3
Find the simple interest and the amount when:
Principal = Rs 1500, rate = 12% p.a. and time = 3 years 3 months.
S o l u t i o n :
P = Rs. 1500, R = 12%, T = 3 +
3
12
=
13
4
years
S.I. =
P×R×T
100
=
1500×12×13
100×4
= Rs. 585
Amount=P+S.I.
=1500+585 =Rs . 2085
Q u e s t i o n : 4
Find the simple interest and the amount when:
Principal = Rs 9600, rate = 7
1
2
%
p.a. and time = 5 months.
S o l u t i o n :
P = Rs. 9600R = 7
1
2
% T = 5 months =
5
12
yearsS. I. =
P×R×T
100
=
9600×15×5
100×2×12
= Rs. 300Amount = P + S. I. = 9600 +300 = Rs. 9900
Q u e s t i o n : 5
Find the simple interest and the amount when:
Principal = Rs 5000, rate = 9% p.a. and time = 146 days.
S o l u t i o n :
P = Rs. 5000 , R = 9% , T = 146 days =
146
365
years
S .I . =
P×R×T
100
=
5000×9×146
100×365
=Rs. 180
Amount=P+S .I .
=5000+180 =Rs . 5180
Q u e s t i o n : 6
Find the time when:
Principal = Rs 6400, SI = Rs 1152 and rate = 6% p.a.
S o l u t i o n :
P = Rs. 6400, S. I. = Rs. 1152, R = 6%
T =
S.I.×100
P×R
=
1152×100
6400×6
=
1152
384
= 3 years
Q u e s t i o n : 7
Find the time when:
Principal = Rs 9540, SI = Rs 1908 and rate = 8% p.a.
S o l u t i o n :
P = Rs. 9540 , S. I. = Rs. 1908, R = 8%
T =
S.I.×100
P×R
=
1908×100
9540×8
=
10
4
=2
1
2
years
Q u e s t i o n : 8
Find the time when:
Principal = Rs 5000, amount = Rs 6450 and rate = 12% p.a.
S o l u t i o n :
P = Rs. 5000, A=Rs. 6450, R = 12%
S. I. = A -P
= 6450 -5000
= Rs. 1450
T =
S.I×100
P×R
=
1450×100
5000×12
=
29
12
= 2
5
12
=2 years 5 months
Q u e s t i o n : 9
Find the rate when:
Principal = Rs 8250, SI = Rs 1100 and time = 2 years.
S o l u t i o n :
P = Rs. 8250, S. I. = Rs. 1100, T = 2 years
R=
S.I.×100
P×T
=
1100×100
8250×2
=
1100
165
=6.67%
Q u e s t i o n : 1 0
Find the rate when:
Principal = Rs 5200, SI = Rs 975 and time = 2
1
2
years.
S o l u t i o n :
P= Rs. 5200 , S.I.=Rs. 975 [ T=2
1
2
years=
5
2
years]
R=
S.I.×100
P×T
=
975×100×2
5200×5
=
195
26
=7.5%
Q u e s t i o n : 1 1
Find the rate when:
Principal = Rs 3560, amount = Rs 4521.20 and time = 3 years.
S o l u t i o n :
P = Rs. 3560 , A = Rs. 4521. 20 , T = 3 years
S. I. = A -P = 4521. 20 -3560
= Rs. 961. 20
R =
S.I.×100
P×T
=
961.20×100
3560×3
=
96120×100
100×3560×3
=9%
Q u e s t i o n : 1 2
Shanta borrowed Rs 6000 from the State Bank of India for 3 years 8 months at 12% per annum. What amount will clear off her debt?
S o l u t i o n :
P = Rs 6000, R = 12%, T=3 years 8 months = 3
8
12
=
44
12
years
S.I. =
P×R×T
100
=
6000×12×44
100×12
= Rs 2640
A = P +S. I.
= 6000 +2640
= Rs 8640
Q u e s t i o n : 1 3
Hari borrowed Rs 12600 from a moneylender at 15% per annum simple interest. After 3 years, he paid Rs 7070 and gave a goat to clear off the debt. What is the cost of the goat?
S o l u t i o n :
P = Rs. 12600 R = 15% T = 3 years
S.I.=
P×R×T
100
=
12600×15×3
100
=Rs. 5670
A = Rs. 12600 +Rs. 5670 = Rs. 18270
Hari had to pay Rs. 18270 to the money lender, but he paid Rs. 7070 and a goat.
? Cost of the goat = Rs. 18270 -Rs. 7070
= Rs. 11200
Q u e s t i o n : 1 4
The simple interest on a certain sum for 3 years at 10% per annum is Rs 829.50. Find the sum.
S o l u t i o n :
Let the sum be Rs. P.
S.I. = Rs. 829. 50, T = 3 years, R = 10%
Now, P=
S.I×100
R×T
=
829.50×100
10×3
=
8295
3
= 2765Hence, the sum is Rs. 2765.
Q u e s t i o n : 1 5
A sum when reckoned at 7
1
2
%
per annum amounts to Rs 3920 in 3 years. Find the sum
S o l u t i o n :
Let the required sum be Rs. x.
A = Rs. 3920, R = 7
1
2
%, T = 3 years
Now,
Now, S.I.=
P×R×T
100
=
x×15×3
2×100
=
9x
40
A = P +S. I.
= x +
9x
40
=
40x+9x
40
=
49x
40
But the amount is Rs. 3920.
= >
49x
40
= 3920
= > x =
3920×40
49
=
156800
49
= 3200
Hence, the required sum is Rs. 3200.
Q u e s t i o n : 1 6
A sum of money put at 11% per annum amounts to Rs 4491 in 2 years 3 months. What will it amount to in 3 years at the same rate?
S o l u t i o n :
Given: R=11%, T=2 years 3 months = 2+
3
12
=
27
12
years
Let the required sum be Rs. x.
S.I.=
P×R×T
100
=
x×11×27
9
100×12 4
=
99x
400
A = P +S. I.
= x +
99x
400
=
400x+99x
400
=
499x
400
But the amount is Rs. 4491.
= >
499x
400
= 4491
= > x =
4491×400
499
=
1796400
499
= 3600
Hence, the required sum is Rs. 3600.
? S.I.=
P×R×T
100
=
3600×11×3
100
= Rs. 1188
? Amount=P+S.I.=3600+1188
=Rs. 4788
Q u e s t i o n : 1 7
A sum of money invested at 8% per annum amounts to Rs 12122 in 2 years. What will it amount to in 2 years 8 months at 9% per annum?
S o l u t i o n :
Let the required sum be Rs. x.
S.I.=
P×R×T
100
=
x×8×2
100
=
16x
100
A = P +S. I.
= x +
16x
100
=
100x+16x
100
=
116x
100
But the amount is Rs. 12122.
= >
116x
100
= 12122
= > x =
12122×100
116
= 10450
Now, S.I.=
P×R×T
100
=
10450×9
3
×32
8
100×12 4 1 = Rs. 2508
? A=P+S.I.
= Rs. 10450 + Rs. 2508
= Rs. 12958
Q u e s t i o n : 1 8
At what rate per cent per annum will Rs 3600 amount to Rs 4734 in 3
1
2
years?
S o l u t i o n :
P = Rs. 3600 A = Rs. 4734 T= 3
1
2
=
7
2
years
S. I. = A -P
= 4734 -3600
= Rs. 1134
R=
S.I.×100
P×T
=
1134×100×2
3600×7
=9%
Q u e s t i o n : 1 9
If Rs 640 amounts to Rs 768 in 2 years 6 months, what will Rs 850 amount to in 3 years at the same rate per cent per annum?
S o l u t i o n :
P = Rs. 640, A = Rs. 768, T=2 years 6 months =
5
2
years
S. I. = A -P
= 768 -640
= Rs. 128
R=
S.I.×100
P×T
=
128×100×2
640×5
=8%
P = Rs. 850, R = 8%, T = 3 years
? S.I. =
P×R×T
100
=
850×8×3
100
=
2040
10
=Rs. 204
? A = P +S. I.
= 850 +204
= Rs. 1054
Q u e s t i o n : 2 0
In what time will Rs 5600 amount to Rs 6720 at 8% per annum?
S o l u t i o n :
P = Rs. 5600, A = Rs. 6720, R = 8%
S. I. = A -P
= 6720 -5600
= Rs. 1120
T=
S.I.×100
P×R
=
1120×100
5600×8
=
1120
448
=2
1
2
years
Q u e s t i o n : 2 1
A sum of money becomes
8
5
of itself in 5 years at a certain rate of simple interest. Find the rate of interest.
S o l u t i o n :
Let the sum be Rs. x .
Amount=
8x
5
? S.I.=A -P=
8x
5
-x
=
3x
5
Let the rate be R%.
S.I.=
P×R×T
100
= >
3x
5
=
x×R×5
1
100 20
= > 3x ×20 = R ×x ×5
= > R =
3×x×20
4
x×5
= 12
Hence, the rate of interest is 12 %.
Q u e s t i o n : 2 2
A sum of money lent at simple interest amounts to Rs 783 in 2 years and to Rs 837 in 3 years. Find the sum and the rate per cent per annum.
S o l u t i o n :
Amount in 3 years = (Principal + S. I. for 3 years) = Rs. 837
Amount in 2 years = (Principal + S. I. for 2 years) = Rs. 783
On subtracting:
S. I. for 1 year = (837 -783) = Rs. 54
S. I. for 2 years=
54
1
×2 = Rs. 108
? Sum = Amount for 2 years -S. I. for 2 years
= 783 -108
= Rs. 675
P = Rs. 675, S. I. = Rs. 108 and T = 2 years
R =
S.I.×100
P×T
=
108×100
50 2
675 27 ×2 1
= 8%
Q u e s t i o n : 2 3
A sum of money lent at simple interest amount to Rs 4745 in 3 years and to Rs 5475 in 5 years. Find the sum and the rate per cent per annum.
S o l u t i o n :
Amount in 5 years = (Principal + S. I. for 5 years) = Rs. 5475
Amount in 3 years = (Principal + S. I. for 3 years) = Rs. 4745
On subtracting:
S. I. for 2 years = (5475 -4745) = Rs. 730
S. I. for 3 years=
730
2
×3 = Rs. 1095
? Sum = Amount for 3 years -S. I. for 3 years
= 4745 -1095
= Rs. 3650
P=Rs. 3650, S.I.=Rs. 1095, T=3 years
R=
S.I.×100
P×T
=
1095×100
3650×3
= 10%
Q u e s t i o n : 2 4
Divide Rs 3000 into two parts such that the simple interest on the first part for 4 years at 8% per annum is equal to the simple interest on the second part for 2 years at 9% per annum.
S o l u t i o n :
( )
( )
Let the first part be Rs. x.
Second part = (3000 -x)
? S. I. on x at 8% per annum for 4 years =
x×8×4
2 1
100 50 25 =
8x
25
S. I. on (3000 -x) at 9% per annum =
3000-x ×9×2
1
100 50
=
27000-9x
50
?
8x
25
=
27000-9x
50
= > 8x =
27000-9x ×25
1
50 2
= > 16x = 27000 -9x
= > 16x +9x = 27000
= > x =
27000
1080
25 1
= 1080
? First part = Rs.1080
Second part = (3000 -1080) = Rs. 1920
Q u e s t i o n : 2 5
Divide Rs 3600 into two parts such that if one part be lent at 9% per annum and the other at 10% per annum, the total annum income is Rs 333.
S o l u t i o n :
Let the first part be Rs. x.
Second part = (3600 -x)
? S. I. on x at 9% per annum for 1 years =
x×9×1
100
=
9x
100
And, S. I. on (3600 -x) at 10% per annum =
3600-x ×1×10
1
100
=
3600-x
10
?
9x
100
+
3600-x
10
= 333
= >
9x+36000-10x
100
= 333
= > -x +36000 = 33300
= > -x = 33300 -36000
= > -x = -2700
= > x = 2700
First part = Rs. 2700
Second part = (3600 -2700) = Rs. 900
Q u e s t i o n : 2 6
Mark
? against the correct answer
The simple interest on Rs 6250 at 4% per annum for 6 months is
a
Rs 125
b
Rs 150
c
Rs 175
d
Rs 135
S o l u t i o n :
(a) Rs. 125Principal = Rs. 6250
Simple Interest = 4% per annum
Time = 6 months =
1
2
years
Simple Interest=
P×R×T
100
Simple Interest=
6250×4×1
100×2
Simple Interest=
250
2
= Rs. 125
Q u e s t i o n : 2 7
Mark
? against the correct answer
A sum amounts to Rs 3605 in 219 days at 5% per annum. The sum is
a
Rs 3250
b
Rs 3500
c
Rs 3400
d
Rs 3550
S o l u t i o n :
b
Rs.3500
Amount =Rs. 3605
Time =
219
365
days=
219
365
days
Rate=5% per ? annum
Amount = Sum +
Sum×Rate×Time
100
Amount = Sum (1+
Rate×Time
100
)
Sum=
3605
1+
5
100
×
219
365
=
3605×36500
37595
Sum= Rs. 3500
( )
( )
( )
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FAQs on RS Aggarwal Solutions: Simple Interest - Mathematics (Maths) Class 7
| 1. What is the formula for calculating simple interest? |  |
Ans. The formula for calculating simple interest is:
Simple Interest = (Principal * Rate * Time) / 100.
| 2. How is simple interest different from compound interest? | |
Ans. Simple interest is calculated only on the principal amount, whereas compound interest is calculated on both the principal amount and the accumulated interest. Compound interest generally yields a higher amount compared to simple interest.
| 3. Can you provide an example of calculating simple interest? | |
Ans. Certainly! Let's say you deposit $500 in a bank account with an annual interest rate of 5%. After 2 years, the simple interest earned can be calculated as follows:
Simple Interest = (500 * 5 * 2) / 100 = $50.
Therefore, the simple interest earned after 2 years would be $50.
| 4. What is the significance of time in calculating simple interest? | |
Ans. Time plays a crucial role in calculating simple interest as it determines the duration for which the principal amount is borrowed or invested. The longer the time period, the higher the interest earned or paid.
| 5. How can simple interest be useful in everyday life? | |
Ans. Simple interest is applicable in various real-life scenarios, such as borrowing or lending money, investing in fixed deposits, or calculating interest on credit card balances. It helps individuals understand the interest they owe or earn on their financial transactions, enabling them to make informed decisions.
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Nov 08, 2024 Last updated |
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Additional Information about RS Aggarwal Solutions: Simple Interest for Class 7 Preparation
RS Aggarwal Solutions: Simple Interest Free PDF Download
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RS Aggarwal Solutions: Simple Interest Notes
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RS Aggarwal Solutions: Simple Interest Class 7 Questions
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The content of RS Aggarwal Solutions: Simple Interest is prepared as per the latest Class 7 syllabus.
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