CMAT 2021 Slot - 2: Previous Year Question Paper with Solutions

 Page 1


CMAT 2021 Slot 2
Quantitative Techniques and Data Interpretation
1. Given: Anuj takes 1 day to complete a job. Bharat takes twice the time as Anuj to complete the same job. Chetan takes twice the
time as Bharat to complete that job. Dhiraj takes twice the time as Chetan to complete that job.
(A) Chetan and Dhiraj will take 8/3 days to complete the work
(B) The second fastest pair to complete the work is Anuj and Dhiraj
(C) The second slowest pair to complete the work is Bharat and Dhiraj
(D) Bharat and Dhiraj will take 4/3 days to complete the work
A    (A), (B) and (C) only
B    (A) and (D) only
C    (A) and (C) only
D    (A) only
A n s w e r : C
Explanation:
Anuj takes 1 day to complete 
Bharat takes 2 days 
Chetan takes 4 days and Dhiraj takes 8 days to complete
option A chetan and Dhiraj together will take so A is correct.
Now calculating for all we get AB in 2/3 days AC in 4/5 days AD in 8/9 days BC in 8/6 days BD in 16/10 days 
So we can say BD is 2nd slowest pair
Hence A and C are correct 
2. How many ten-digit numbers can be formed using all the digits of 2435753228 such that odd digits appear only in even places?
A    
B    
C    
D    
A n s w e r : D
Explanation:
we have : 2435753228 
Now here we have 5 odd digits and 5 even digits and total 10 places 
so 5,5,3,3,7 will arrange in 5 places and 2,2,2,8,4 will arrange in 5 places 
we get : total arrangements =
we get  
3. Given below are two statements
Statement I :  is equivalent to 
Statement II : The last 4 bits in the binary representation of a multiple of 16 is 1000.
In light of the above statements, choose the correct answer from the options given below
A    Both Statement I and Statement II are true
B    Both Statement I and Statement II are false
= 4+8
4× 8
= 12
32
d a y s 3 
8
2!3!5!
(5!)
2
3!
(5!)
2
3!(2!)
2
(5!)
2
× 3!
5!
2!× 2!
5!
3! 2! ( )
2
5! ( )
2
(543)6 (317)8
  
.
Page 2


CMAT 2021 Slot 2
Quantitative Techniques and Data Interpretation
1. Given: Anuj takes 1 day to complete a job. Bharat takes twice the time as Anuj to complete the same job. Chetan takes twice the
time as Bharat to complete that job. Dhiraj takes twice the time as Chetan to complete that job.
(A) Chetan and Dhiraj will take 8/3 days to complete the work
(B) The second fastest pair to complete the work is Anuj and Dhiraj
(C) The second slowest pair to complete the work is Bharat and Dhiraj
(D) Bharat and Dhiraj will take 4/3 days to complete the work
A    (A), (B) and (C) only
B    (A) and (D) only
C    (A) and (C) only
D    (A) only
A n s w e r : C
Explanation:
Anuj takes 1 day to complete 
Bharat takes 2 days 
Chetan takes 4 days and Dhiraj takes 8 days to complete
option A chetan and Dhiraj together will take so A is correct.
Now calculating for all we get AB in 2/3 days AC in 4/5 days AD in 8/9 days BC in 8/6 days BD in 16/10 days 
So we can say BD is 2nd slowest pair
Hence A and C are correct 
2. How many ten-digit numbers can be formed using all the digits of 2435753228 such that odd digits appear only in even places?
A    
B    
C    
D    
A n s w e r : D
Explanation:
we have : 2435753228 
Now here we have 5 odd digits and 5 even digits and total 10 places 
so 5,5,3,3,7 will arrange in 5 places and 2,2,2,8,4 will arrange in 5 places 
we get : total arrangements =
we get  
3. Given below are two statements
Statement I :  is equivalent to 
Statement II : The last 4 bits in the binary representation of a multiple of 16 is 1000.
In light of the above statements, choose the correct answer from the options given below
A    Both Statement I and Statement II are true
B    Both Statement I and Statement II are false
= 4+8
4× 8
= 12
32
d a y s 3 
8
2!3!5!
(5!)
2
3!
(5!)
2
3!(2!)
2
(5!)
2
× 3!
5!
2!× 2!
5!
3! 2! ( )
2
5! ( )
2
(543)6 (317)8
  
.
C    
Statement I is true but Statement II is false
D    Statement I is false but Statement II is true
A n s w e r : C
Explanation:
543 in base 6 expressed in decimal form =5(36)+4(6)+3 =207
317 in base 8 expressed in decimal form = 3(64)+8+7 =207
So statement 1 is correct
Now 16 in base 2 = 10000
32 in base 2 = 100000
Therefore statement 2 is false 
Hence C is the correct answer 
4. During the next year, the probability that a Company A releases a mobile is 0.7. The probability that mobile is a success. given
that it is released by the Company is 0.8. The probability that a mobile is a success and released by a Company B is 0.28. A
mobile released by either Company A or Company B during the next one year is a success. Find the probability that it is released
by Company A.
A    
B    
C    
D    
A n s w e r : C
Explanation:
Probability that A releases a mobile = 0.7
Probability that mobile is a success given that it is released by A = 0.8
Probability that mobile is released by A and is success = 0.8*0.7 = 0.56
And probability that mobile is a success and released by B = 0.28
Total probability for success = 0.56+0.28 = 0.84
Now Probability that it is success and is released by A = 0.56/0.84 = 2/3
5. If a is  times of b, b is th of c and d is th of c, the ratio of a and d is
A    8:3
B    9:1
C    8:1
D    9:2
A n s w e r : D
Explanation:
b= and 
d=
c=4d
Now substituting we get 
so we get a=
a:d=9:2
3
1
2
1
3
2
4
3
2
3
4
3
4
1
a = b 2
3
c 4
3
4
c
a = × 2
3
× 4
3
4 d
a = d 2
9
  
.
Page 3


CMAT 2021 Slot 2
Quantitative Techniques and Data Interpretation
1. Given: Anuj takes 1 day to complete a job. Bharat takes twice the time as Anuj to complete the same job. Chetan takes twice the
time as Bharat to complete that job. Dhiraj takes twice the time as Chetan to complete that job.
(A) Chetan and Dhiraj will take 8/3 days to complete the work
(B) The second fastest pair to complete the work is Anuj and Dhiraj
(C) The second slowest pair to complete the work is Bharat and Dhiraj
(D) Bharat and Dhiraj will take 4/3 days to complete the work
A    (A), (B) and (C) only
B    (A) and (D) only
C    (A) and (C) only
D    (A) only
A n s w e r : C
Explanation:
Anuj takes 1 day to complete 
Bharat takes 2 days 
Chetan takes 4 days and Dhiraj takes 8 days to complete
option A chetan and Dhiraj together will take so A is correct.
Now calculating for all we get AB in 2/3 days AC in 4/5 days AD in 8/9 days BC in 8/6 days BD in 16/10 days 
So we can say BD is 2nd slowest pair
Hence A and C are correct 
2. How many ten-digit numbers can be formed using all the digits of 2435753228 such that odd digits appear only in even places?
A    
B    
C    
D    
A n s w e r : D
Explanation:
we have : 2435753228 
Now here we have 5 odd digits and 5 even digits and total 10 places 
so 5,5,3,3,7 will arrange in 5 places and 2,2,2,8,4 will arrange in 5 places 
we get : total arrangements =
we get  
3. Given below are two statements
Statement I :  is equivalent to 
Statement II : The last 4 bits in the binary representation of a multiple of 16 is 1000.
In light of the above statements, choose the correct answer from the options given below
A    Both Statement I and Statement II are true
B    Both Statement I and Statement II are false
= 4+8
4× 8
= 12
32
d a y s 3 
8
2!3!5!
(5!)
2
3!
(5!)
2
3!(2!)
2
(5!)
2
× 3!
5!
2!× 2!
5!
3! 2! ( )
2
5! ( )
2
(543)6 (317)8
  
.
C    
Statement I is true but Statement II is false
D    Statement I is false but Statement II is true
A n s w e r : C
Explanation:
543 in base 6 expressed in decimal form =5(36)+4(6)+3 =207
317 in base 8 expressed in decimal form = 3(64)+8+7 =207
So statement 1 is correct
Now 16 in base 2 = 10000
32 in base 2 = 100000
Therefore statement 2 is false 
Hence C is the correct answer 
4. During the next year, the probability that a Company A releases a mobile is 0.7. The probability that mobile is a success. given
that it is released by the Company is 0.8. The probability that a mobile is a success and released by a Company B is 0.28. A
mobile released by either Company A or Company B during the next one year is a success. Find the probability that it is released
by Company A.
A    
B    
C    
D    
A n s w e r : C
Explanation:
Probability that A releases a mobile = 0.7
Probability that mobile is a success given that it is released by A = 0.8
Probability that mobile is released by A and is success = 0.8*0.7 = 0.56
And probability that mobile is a success and released by B = 0.28
Total probability for success = 0.56+0.28 = 0.84
Now Probability that it is success and is released by A = 0.56/0.84 = 2/3
5. If a is  times of b, b is th of c and d is th of c, the ratio of a and d is
A    8:3
B    9:1
C    8:1
D    9:2
A n s w e r : D
Explanation:
b= and 
d=
c=4d
Now substituting we get 
so we get a=
a:d=9:2
3
1
2
1
3
2
4
3
2
3
4
3
4
1
a = b 2
3
c 4
3
4
c
a = × 2
3
× 4
3
4 d
a = d 2
9
  
.
6. Pipe X can fill a tank in 12 hours and pipe Y can empty the tank in 18 hours. Both pipes are opened at 8 am and after some time
Y is closed, and the tank is full at 10 pm on the same day. At what time was pipe Y closed?
A    1 pm
B    10 am
C    11 am
D    12 noon
A n s w e r : C
Explanation:
Let volume be 36 units 
so X fills at 3 units per hour and Y empties at 2 units per hour
Now Tank was filled in 14 hrs so X filled 14*3 =42 units 
Now therefore Y emptied 6 units 
so it will empty 6 units in 3 hours
so Y will be closed at 11 am
7. The price of an apple is twice that of an orange. The price of an orange is thrice that of a banana.If the price of an apple
increases by 10%, price of an orange increases by 30% and the price of a banana increases by 20%. Find the percentage
increase in the price of 20 apples, 20 oranges and 20 bananas.
A    19%
B    17%
C    15%
D    13%
A n s w e r : B
Explanation:
Let price of banana be x 
so price of orange = 3x 
and price of apple will be 6x
Price of 20 bananas , apples and oranges = 200 x  (1)
Now f the price of an apple increases by 10%,
it becomes = 6.6x
so price of 20 apples = 132x
if price of an orange increases by 30% it becomes = 3.9x 
so price of 20 oranges = 78x
if price of a banana increases by 20% 
it becomes 1.2 x
so price of 20 bananas = 24x 
Now total price of 20 bananas , apples and oranges =234x  (2)
So Percentage change in price = %
    
8. The difference between the compound interest and simple interest for two years on a certain sum at a certain rate of interest is
Rs. 64. The compound interest for two years is Rs. 704. The principal is
A    800
× 200 x
234 x-200 x
100 = 17
  
.
Page 4


CMAT 2021 Slot 2
Quantitative Techniques and Data Interpretation
1. Given: Anuj takes 1 day to complete a job. Bharat takes twice the time as Anuj to complete the same job. Chetan takes twice the
time as Bharat to complete that job. Dhiraj takes twice the time as Chetan to complete that job.
(A) Chetan and Dhiraj will take 8/3 days to complete the work
(B) The second fastest pair to complete the work is Anuj and Dhiraj
(C) The second slowest pair to complete the work is Bharat and Dhiraj
(D) Bharat and Dhiraj will take 4/3 days to complete the work
A    (A), (B) and (C) only
B    (A) and (D) only
C    (A) and (C) only
D    (A) only
A n s w e r : C
Explanation:
Anuj takes 1 day to complete 
Bharat takes 2 days 
Chetan takes 4 days and Dhiraj takes 8 days to complete
option A chetan and Dhiraj together will take so A is correct.
Now calculating for all we get AB in 2/3 days AC in 4/5 days AD in 8/9 days BC in 8/6 days BD in 16/10 days 
So we can say BD is 2nd slowest pair
Hence A and C are correct 
2. How many ten-digit numbers can be formed using all the digits of 2435753228 such that odd digits appear only in even places?
A    
B    
C    
D    
A n s w e r : D
Explanation:
we have : 2435753228 
Now here we have 5 odd digits and 5 even digits and total 10 places 
so 5,5,3,3,7 will arrange in 5 places and 2,2,2,8,4 will arrange in 5 places 
we get : total arrangements =
we get  
3. Given below are two statements
Statement I :  is equivalent to 
Statement II : The last 4 bits in the binary representation of a multiple of 16 is 1000.
In light of the above statements, choose the correct answer from the options given below
A    Both Statement I and Statement II are true
B    Both Statement I and Statement II are false
= 4+8
4× 8
= 12
32
d a y s 3 
8
2!3!5!
(5!)
2
3!
(5!)
2
3!(2!)
2
(5!)
2
× 3!
5!
2!× 2!
5!
3! 2! ( )
2
5! ( )
2
(543)6 (317)8
  
.
C    
Statement I is true but Statement II is false
D    Statement I is false but Statement II is true
A n s w e r : C
Explanation:
543 in base 6 expressed in decimal form =5(36)+4(6)+3 =207
317 in base 8 expressed in decimal form = 3(64)+8+7 =207
So statement 1 is correct
Now 16 in base 2 = 10000
32 in base 2 = 100000
Therefore statement 2 is false 
Hence C is the correct answer 
4. During the next year, the probability that a Company A releases a mobile is 0.7. The probability that mobile is a success. given
that it is released by the Company is 0.8. The probability that a mobile is a success and released by a Company B is 0.28. A
mobile released by either Company A or Company B during the next one year is a success. Find the probability that it is released
by Company A.
A    
B    
C    
D    
A n s w e r : C
Explanation:
Probability that A releases a mobile = 0.7
Probability that mobile is a success given that it is released by A = 0.8
Probability that mobile is released by A and is success = 0.8*0.7 = 0.56
And probability that mobile is a success and released by B = 0.28
Total probability for success = 0.56+0.28 = 0.84
Now Probability that it is success and is released by A = 0.56/0.84 = 2/3
5. If a is  times of b, b is th of c and d is th of c, the ratio of a and d is
A    8:3
B    9:1
C    8:1
D    9:2
A n s w e r : D
Explanation:
b= and 
d=
c=4d
Now substituting we get 
so we get a=
a:d=9:2
3
1
2
1
3
2
4
3
2
3
4
3
4
1
a = b 2
3
c 4
3
4
c
a = × 2
3
× 4
3
4 d
a = d 2
9
  
.
6. Pipe X can fill a tank in 12 hours and pipe Y can empty the tank in 18 hours. Both pipes are opened at 8 am and after some time
Y is closed, and the tank is full at 10 pm on the same day. At what time was pipe Y closed?
A    1 pm
B    10 am
C    11 am
D    12 noon
A n s w e r : C
Explanation:
Let volume be 36 units 
so X fills at 3 units per hour and Y empties at 2 units per hour
Now Tank was filled in 14 hrs so X filled 14*3 =42 units 
Now therefore Y emptied 6 units 
so it will empty 6 units in 3 hours
so Y will be closed at 11 am
7. The price of an apple is twice that of an orange. The price of an orange is thrice that of a banana.If the price of an apple
increases by 10%, price of an orange increases by 30% and the price of a banana increases by 20%. Find the percentage
increase in the price of 20 apples, 20 oranges and 20 bananas.
A    19%
B    17%
C    15%
D    13%
A n s w e r : B
Explanation:
Let price of banana be x 
so price of orange = 3x 
and price of apple will be 6x
Price of 20 bananas , apples and oranges = 200 x  (1)
Now f the price of an apple increases by 10%,
it becomes = 6.6x
so price of 20 apples = 132x
if price of an orange increases by 30% it becomes = 3.9x 
so price of 20 oranges = 78x
if price of a banana increases by 20% 
it becomes 1.2 x
so price of 20 bananas = 24x 
Now total price of 20 bananas , apples and oranges =234x  (2)
So Percentage change in price = %
    
8. The difference between the compound interest and simple interest for two years on a certain sum at a certain rate of interest is
Rs. 64. The compound interest for two years is Rs. 704. The principal is
A    800
× 200 x
234 x-200 x
100 = 17
  
.
B    
1600
C    2400
D    3200
A n s w e r : B
Explanation:
We have 
And 
Now dividing both we get :
Solving we get R/100 = 5
Now substituting we get P = 64*25 = 1600
9. A vessel has 500 litres of milk. 50 litres of milk is replaced with 50 litres of water in this vessel. If this operation is repeated
another 2 more times, whatis the percentage of milk in the vessel at the end?
A    70.0
B    72.9
C    80.0
D    81.0
A n s w e r : B
Explanation:
We have formula :
F = 
Here n =3 V =500 k =50 
substituting we get 
F/I = 729/1000
Therefore in percentage F = 72.9 percent
10. A started a business with Rs. 50000. After three months, B joins with an investment of Rs. 60000 and A withdraws Rs. 10000
out of his capital. Three months later, B brought in Rs. 20000 more. At the end of the year, what should be the ratio in which they
A and B share the profits?
A    22:15
B    13:22
C    17:22
D    15:22
A n s w e r : C
Explanation:
Profit share = Investment * Time period 
Now we get ratio of profit of A and B :
we get ratio as 
P = ( 100
R
)
2
64
P 1 + - ( ( 100
R
) )
2
p = 704
 = 
1+ -1 ( 100
R
)
2
( 100
R
)
2
11
1
I 1 - (
V ( )
K
)
n
60,000× 3 + 80,000× 6
50,000× 3 + 40,000× 9
= 660 
510
22
17
  
.
Page 5


CMAT 2021 Slot 2
Quantitative Techniques and Data Interpretation
1. Given: Anuj takes 1 day to complete a job. Bharat takes twice the time as Anuj to complete the same job. Chetan takes twice the
time as Bharat to complete that job. Dhiraj takes twice the time as Chetan to complete that job.
(A) Chetan and Dhiraj will take 8/3 days to complete the work
(B) The second fastest pair to complete the work is Anuj and Dhiraj
(C) The second slowest pair to complete the work is Bharat and Dhiraj
(D) Bharat and Dhiraj will take 4/3 days to complete the work
A    (A), (B) and (C) only
B    (A) and (D) only
C    (A) and (C) only
D    (A) only
A n s w e r : C
Explanation:
Anuj takes 1 day to complete 
Bharat takes 2 days 
Chetan takes 4 days and Dhiraj takes 8 days to complete
option A chetan and Dhiraj together will take so A is correct.
Now calculating for all we get AB in 2/3 days AC in 4/5 days AD in 8/9 days BC in 8/6 days BD in 16/10 days 
So we can say BD is 2nd slowest pair
Hence A and C are correct 
2. How many ten-digit numbers can be formed using all the digits of 2435753228 such that odd digits appear only in even places?
A    
B    
C    
D    
A n s w e r : D
Explanation:
we have : 2435753228 
Now here we have 5 odd digits and 5 even digits and total 10 places 
so 5,5,3,3,7 will arrange in 5 places and 2,2,2,8,4 will arrange in 5 places 
we get : total arrangements =
we get  
3. Given below are two statements
Statement I :  is equivalent to 
Statement II : The last 4 bits in the binary representation of a multiple of 16 is 1000.
In light of the above statements, choose the correct answer from the options given below
A    Both Statement I and Statement II are true
B    Both Statement I and Statement II are false
= 4+8
4× 8
= 12
32
d a y s 3 
8
2!3!5!
(5!)
2
3!
(5!)
2
3!(2!)
2
(5!)
2
× 3!
5!
2!× 2!
5!
3! 2! ( )
2
5! ( )
2
(543)6 (317)8
  
.
C    
Statement I is true but Statement II is false
D    Statement I is false but Statement II is true
A n s w e r : C
Explanation:
543 in base 6 expressed in decimal form =5(36)+4(6)+3 =207
317 in base 8 expressed in decimal form = 3(64)+8+7 =207
So statement 1 is correct
Now 16 in base 2 = 10000
32 in base 2 = 100000
Therefore statement 2 is false 
Hence C is the correct answer 
4. During the next year, the probability that a Company A releases a mobile is 0.7. The probability that mobile is a success. given
that it is released by the Company is 0.8. The probability that a mobile is a success and released by a Company B is 0.28. A
mobile released by either Company A or Company B during the next one year is a success. Find the probability that it is released
by Company A.
A    
B    
C    
D    
A n s w e r : C
Explanation:
Probability that A releases a mobile = 0.7
Probability that mobile is a success given that it is released by A = 0.8
Probability that mobile is released by A and is success = 0.8*0.7 = 0.56
And probability that mobile is a success and released by B = 0.28
Total probability for success = 0.56+0.28 = 0.84
Now Probability that it is success and is released by A = 0.56/0.84 = 2/3
5. If a is  times of b, b is th of c and d is th of c, the ratio of a and d is
A    8:3
B    9:1
C    8:1
D    9:2
A n s w e r : D
Explanation:
b= and 
d=
c=4d
Now substituting we get 
so we get a=
a:d=9:2
3
1
2
1
3
2
4
3
2
3
4
3
4
1
a = b 2
3
c 4
3
4
c
a = × 2
3
× 4
3
4 d
a = d 2
9
  
.
6. Pipe X can fill a tank in 12 hours and pipe Y can empty the tank in 18 hours. Both pipes are opened at 8 am and after some time
Y is closed, and the tank is full at 10 pm on the same day. At what time was pipe Y closed?
A    1 pm
B    10 am
C    11 am
D    12 noon
A n s w e r : C
Explanation:
Let volume be 36 units 
so X fills at 3 units per hour and Y empties at 2 units per hour
Now Tank was filled in 14 hrs so X filled 14*3 =42 units 
Now therefore Y emptied 6 units 
so it will empty 6 units in 3 hours
so Y will be closed at 11 am
7. The price of an apple is twice that of an orange. The price of an orange is thrice that of a banana.If the price of an apple
increases by 10%, price of an orange increases by 30% and the price of a banana increases by 20%. Find the percentage
increase in the price of 20 apples, 20 oranges and 20 bananas.
A    19%
B    17%
C    15%
D    13%
A n s w e r : B
Explanation:
Let price of banana be x 
so price of orange = 3x 
and price of apple will be 6x
Price of 20 bananas , apples and oranges = 200 x  (1)
Now f the price of an apple increases by 10%,
it becomes = 6.6x
so price of 20 apples = 132x
if price of an orange increases by 30% it becomes = 3.9x 
so price of 20 oranges = 78x
if price of a banana increases by 20% 
it becomes 1.2 x
so price of 20 bananas = 24x 
Now total price of 20 bananas , apples and oranges =234x  (2)
So Percentage change in price = %
    
8. The difference between the compound interest and simple interest for two years on a certain sum at a certain rate of interest is
Rs. 64. The compound interest for two years is Rs. 704. The principal is
A    800
× 200 x
234 x-200 x
100 = 17
  
.
B    
1600
C    2400
D    3200
A n s w e r : B
Explanation:
We have 
And 
Now dividing both we get :
Solving we get R/100 = 5
Now substituting we get P = 64*25 = 1600
9. A vessel has 500 litres of milk. 50 litres of milk is replaced with 50 litres of water in this vessel. If this operation is repeated
another 2 more times, whatis the percentage of milk in the vessel at the end?
A    70.0
B    72.9
C    80.0
D    81.0
A n s w e r : B
Explanation:
We have formula :
F = 
Here n =3 V =500 k =50 
substituting we get 
F/I = 729/1000
Therefore in percentage F = 72.9 percent
10. A started a business with Rs. 50000. After three months, B joins with an investment of Rs. 60000 and A withdraws Rs. 10000
out of his capital. Three months later, B brought in Rs. 20000 more. At the end of the year, what should be the ratio in which they
A and B share the profits?
A    22:15
B    13:22
C    17:22
D    15:22
A n s w e r : C
Explanation:
Profit share = Investment * Time period 
Now we get ratio of profit of A and B :
we get ratio as 
P = ( 100
R
)
2
64
P 1 + - ( ( 100
R
) )
2
p = 704
 = 
1+ -1 ( 100
R
)
2
( 100
R
)
2
11
1
I 1 - (
V ( )
K
)
n
60,000× 3 + 80,000× 6
50,000× 3 + 40,000× 9
= 660 
510
22
17
  
.
     
11. In a company there are 252 engineers, in which the ratio of the number of electronics engineers and computer engineers is 2 : 1.
The ratio of the number of electronics engineers and computer engineers becomes 1:1 after recruitment of some more
computer engineers. The average age of all the engineers is now 22 years and the average age of the computer engineers is 2
years less than the average age of electronics engineers.
(A) The average age (in years) of electronics engineers is 21
(B) The average age (in years) of computer engineers is 21
(C) The average age (in years) of electronics engineers is 23
(D) The average age (in years) of electronics engineers is 25
(E) The average age (in years) of computer engineers is 23
Choose the correct answer from the options given below:
A    (A) and (E)only
B    (B) and (C) only
C    (D) and (E) only
D    (E) only
A n s w e r : B
Explanation:
Number of electronics engineers initially = 
So number of computer engineers initially = 252-168 =84
Now number of computer engineers recruited to make ratio 1:1 = 168-84 =84
Let average age of computer engineers be x
so total age  will be 168x 
Now average age of electronics engineers will be : x+2
So total age will be : (x+2) 168
Now as per given 
Total age = 336(22) 
Equating we get :
336(22) = 336(x+1)
we get x=21 
so B and C are correct
12. In triangle PQR. PS is perpendicular to QR and S divides QR in the ratio of 3 : 1 internally. If PQ=21 and PR =9,find QR.
A    
B    
C    
D    
A n s w e r : D
Explanation:
we have :
× 3
2
252 = 168
18
5
16
5
15
5
12
5
  
.