Averages Quiz Set 019

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Question 1

There are three sections in school with 40, 40 and 40 students respectively. The average weight of a student in these sections, respectively, is 3, 3 and 2 Kg. What is the average weight of all the the students of the combined sections?

 A

$2{2/3}$.

 B

$2{27/40}$.

 C

$2{79/120}$.

 D

$2{13/20}$.

Soln.
Ans: a

The sums of the weights of all the students is 40 × 3 + 40 × 3 + 40 × 2 = 320. The required average = 320/total students = $320/{40 + 40 + 40}$ = ${8/3}$, which is same as: $2{2/3}$.


Question 2

The average number of visitors at a zoo on a Monday is 156, whereas it is 162 on other days of the week. What will be the average number of visitors in a 30-day month that begins on a Monday?

 A

161.

 B

162.

 C

160.

 D

159.

Soln.
Ans: a

The month begins on a Monday, so there will be 5 Mondays. The average = ${5 × 156 + 25 × 162}/30$, which equals ${780 + 4050}/30$ = 161.


Question 3

Average marks of class of 28 students is 51. What will be the average if each student is given 7 as grace marks?

 A

58.

 B

59.

 C

57.

 D

56.

Soln.
Ans: a

Let the total score of the class before grace marks be x. Then, by average formula $51 = x/28$, which gives x = $51 × 28 = 1428$. When grace marks = 7 are added for each of the 28 students, the new total becomes $1428 + 28 × 7 = 1624$, the new average becomes $1624/28 = 58$. TIP: As a shortcut, the new average = old average + grace marks.


Question 4

A, B and C are three numbers. The average of A, B and C is 25. The average of A and B is 14, and the average of B and C is 49, what is the value of number B?

 A

51.

 B

52.

 C

50.

 D

49.

Soln.
Ans: a

By the given conditions, A + B = 2 × 14 = 28. Similarly, B + C = 2 × 49 = 98. Adding we get A + 2B + C = 126. We have also been given that A + B + C = 3 × 25 = 75. Subtracting, we get B = 126 - 75 = 51.


Question 5

What is the increase in the average of 10 numbers if the number 5 is replaced by 85?

 A

8.

 B

9.

 C

7.

 D

10.

Soln.
Ans: a

If a number r is replaced by a number R, the increase/decrease of average is determined according to the formula $(R - r)/n$. So in our case we have R = 85, r = 5, n = 10. So increase = $(85 - 5)/10$ = 8.


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This Blog Post/Article "Averages Quiz Set 019" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-04-07.

Posted by Parveen(Hoven),
Aptitude Trainer


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