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The ratio between the present ages of A and B is 4:5. If the difference between their present ages is 8 yrs, what is the sum of their present ages?
The ratio between the present ages of A and B is 4:5.
A/B = 4/5 ⇒ 5A = 4B ⇒ 5A  4B = 0 .....(1)
If the difference between their present ages is 8 yrs
A  B = 8 .....(2)
multiplying 5 both sides in equation(2)
⇒ 5(A  B) = 40
⇒ 5A  5B = 40
Subtracting equation (1) from equation (2) we get
B = 40
5A = 4B
⇒ 5A = 4 x 40 = 160
⇒ A = 160/5 = 32
Sum of present ages = 40 + 32 = 72
The minute hand of clock is √21 cm long. The area described by a minute hand on the face of the clock between 7 am and 7.05 am is
Given that length of minute hand of clock is √21 cm
Angle described by the minute hand in 60 minutes = 360^{o}
Angle described by the minute hand in 5 minutes = 360/60 x 5 = 30^{o}
We know that Area of sector = θ/360 x πr^{2}
= 30/360 x 22/7 x √21 x √21
= 11/2 = 5.5 cm^{2}
A sum of moeny doubles itself in 10 years at simple interest. What is the rate of interest ?
Let sum of money be x
Then SI = x
⇒ SI = P x R x T/100
⇒ R = SI x 100/P x 10 = 10%
If 7^{1 + x } + 7^{1 − x} = 50, then x =
7(7^{x}) + 7/7^{x} = 50
Let 7^{x} = y
AB∥CD and P is a point between the lines, the measure of the angles ∠ABP+∠BPD+∠CDP is
If the ratio of the areas of two similar triangles is 48:32, then the ratio of the lengths of their corresponding sides is
The HCF and LCM of two numbers are 12 and 72 respectively. If the sum of the two numbers is 60,then one of the two numbers will be
H.C.F = 12, L.C.M = 72
Let one number be = x, then other number = 60  x
Now, x x (60  x) = 12 x 72
or 60x  x^{2} = 864
or x^{2}  60x + 864 = 0
or (x  36) (x  24) = 0
or x = 36 , 24
In questions below, equations have become wrong due to wrong orders of signs. Choose the correct order of signs from the alternative given.
56×6÷3=292
Mr. kalia invested a total amount of Rs. 16500 for two years in two schemes A and B with rate of simple interest 10% per annum and 12% per annum, respectively. If the total amount of interest earned was Rs.3620, what was amount invested in scheme A?
% interest on total amount per annum
Hence, ratio of amount invested in schemes
A and B
Hence, amount invested in A
What should come in the place of the (?) in the following equation? 28/? = ?/112
If v is the variance and σ is the standard deviation, then
There are six teachers A, B, C, D, E and F in a school. Each of the teachers teaches two subjects, one compulsory subject and the other optional subject. D's optional subject is History while three others have it as compulsory subject. E and F have Physics as one of their subjects. F's compulsory subject is Mathematics which is an optional subject of both C and E. History and English are A's subjects but in terms of compulsory and optional subjects, they are reverse of those of D's. Chemistry is an optional subject of any one of them. There is only one female teacher in the school who has English as her compulsory subject.
Q. What is C's compulsory subject?
There are six teachers A, B, C, D, E and F in a school. Each of the teachers teaches two subjects, one compulsory subject and the other optional subject. D's optional subject is History while three others have it as compulsory subject. E and F have Physics as one of their subjects. F's compulsory subject is Mathematics which is an optional subject of both C and E. History and English are A's subjects but in terms of compulsory and optional subjects, they are reverse of those of D's. Chemistry is an optional subject of any one of them. There is only one female teacher in the school who has English as her compulsory subject.
Q. Who is a female member in the group?
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