Aptitude - Averages Online Quiz


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Following quiz provides Multiple Choice Questions (MCQs) related to Averages. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Questions and Answers

Q 1 - If in a class room r boys is the average age in a year. What should be the average of remaining boys if b is the average age of s boys out of them?

A - (ra-sb)/(r-s)

B - (ra-sb)/(s-b)

C - (sa-sb)/(b-s)

D - (ra-sb)/(r+s)

Answer : A

Explanation

r boys have the sum of the age = (ra ) years.
s  boys have the sum of the age = (sb) years.
(r-s) boys have the sum of the ages = (ra-sb)
(r-s) boys have the average of the ages = (ra-sb)/ (r-s).

Q 2 - 15 year is the average age of 24 boys and their teacher also. The average became 14 years if we leave the teacher age. In that case what should be the age of teacher?

A - 67 years

B - 34 years

C - 45 years

D - 39 years

Answer : D

Explanation

24 boys and 1 teacher have sum of the ages= (15*25) =375 years
24 boys have the sum of the ages =  (24*14) =336 years.
Its proves that the age of the teacher =  (375- 336)= 39 years.

Q 3 - A man have 65 kg weight in group if this person interchange with new person then the average weight of 8 man expended by 1.5 kg . What should be the weight of that new man?

A - 77 kg

B - 45 kg

C - 23 kg

D - 67 kg

Answer : A

Explanation

Weight increase = 1.5*8 = 12 kg.
With the help of this  increase weight we find that the weight of the new men is (65+12)= 77.

Q 4 - What should be the average speed of the train if first 12 min. travelled by train at a speed of 30km/hr and after that speed increased and with the speed of 45km/hr travelled for next 8 min?

A - 36 km/hr

B - 26 km/hr

C - 22 km/hr

D - 23 km/hr

Answer : A

Explanation

Total covered distance by train = (30*12/60+45* 8/60) = 12 km
Total time taken by train  to cover the distance = 12+8 = 20min = 1/3 hours.
Required  average speed = 12*3/1 = 36 km/hr.

Q 5 - find out the total value of 6 numbers if 45 is the arithmetic mean of 6 numbers.

A - 230

B - 220

C - 210

D - 270

Answer : D

Explanation

a,b,c,d,e,f is the given 6 numbers  .Then ,
(a+b+c+d+e+f)/6 = 45  = (a+b+c+d+e+f) = 45*6 = 270.
Sum of the given numbers = 270.

Q 6 - 7 is the average of 15 numbers. 6.5 is the average of first 8 numbers and 9.5 is the average of last 8 numbers. What should be the value of middle number?

A - 23

B - 24

C - 36

D - 27

Answer : A

Explanation

middle number = (8* 6.5) +(8*9.5)-(15*7)
= (52+76- 105) = 23

Q 7 - The average score of a cricketer for ten matches is 38.9 runs. If the average for the first six matches is 42, then find the average for the last four matches?

A - 33.25

B - 34.25

C - 33.5

D - 35

Answer - B

Explanation

Required average = (38.9 x 10) - (42 x 6)4 = 1374 = 34.25.

Q 8 - If the arithmetic mean of seventy-five numbers is calculated, it is 35. If each number is increased by 5, then mean of new number is?

A - 70

B - 90

C - 30

D - 40

Answer - D

Explanation

A.M. of 75 numbers = 35. 
Sum of 75 numbers = (75 x 35) = 2625. 
Total increase = (75 x 5) = 375. 
Increased sum = (2625 + 375) = 3000. 
Increased average = 300075 = 40.

Q 9 - A cricketer has a certain average for 10 innings. In the eleventh inning, he scored 108 runs, thereby increasing his average by 6 runs. His new average is?

A - 52

B - 48

C - 55

D - 60

Answer - B

Explanation

Let average for 10 innings be z. Then, 
= 10z + 10811 = 11z + 66 = 10z + 108 = z = 42. 

New average = (z + 6) = 48 runs.

Q 10 - The average weight of 3 men A, B, C is 84 kg. Another man D joins the group and the average now becomes 80kg. If another man E, whose weight is 3 kg more than that of D, replaces A, then the average weight of B, C, D, E becomes 79kg. The weight of A is?

A - 70

B - 75

C - 72

D - 70

Answer - B

Explanation

Let A, B, C, D and E represent their respective weights. Then, 
A + B + C = (84 x 3) = 252 kg, 

A + B + C + D = (80 x 4) = 320 kg. 
D = (320 - 252)kg = 68 kg, 
E = (68 + 3)kg = 71 kg. 

B + C + D + E =  (79 x 4) = 316 kg 
Now, (A + B + C + D) - (B + C + D + E) = (320 - 316)kg = 4 kg 
 
A - E = 4 
A = ( 4 + E ) = 75 kg.

aptitude_averages.htm

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