Quantitative Aptitude

Averages

1,527 Questions
All Basic average and reverse calculation 405 Adding or removing an observation 342 Weighted and combined averages 320 Replacement and correction of a recorded value 233 Ratio shortcut for two-group mixtures 111 Equal-distance average speed 59 Age, score, weight, and spending applications 32 Consecutive terms and arithmetic progressions 25

Averages Questions

Multiple choice

Five friends purchased some books from a book shop. Four of them purchased books worth \$30 each. If the fifth one purchased books worth \$40 more than the average of all of them together, what was the total cost of the books purchased by all?
  1. $140
  2. $160
  3. $180
  4. $200
  5. $220
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the total cost be T. Average = T/5. The fifth person paid 30 + 30 + 30 + 30 + (T/5 + 40) = T. 120 + T/5 + 40 = T. 160 = 4T/5. T = 160 * 5 / 4 = 200.

Multiple choice

In a set of three numbers, the average of first two numbers is 21, the average of the last two numbers is 24, and the average of the first and the last numbers is 15. What is the average of the three numbers?

  1. 20

  2. 60

  3. 25

  4. 18
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let the numbers be x, y, z. (x+y)/2 = 21 => x+y=42. (y+z)/2 = 24 => y+z=48. (x+z)/2 = 15 => x+z=30. Adding these: 2(x+y+z) = 42+48+30 = 120, so x+y+z = 60. The average is (x+y+z)/3 = 60/3 = 20.

Multiple choice

In a club, there are 12 wrestlers. When a wrestler, whose weight is 90 kg, leaves the club, he is replaced by a new wrestler. Then, the average weight of this 12-member club increases by 0.75 kg. What is the weight (in kg) of the new wrestler who joins the club?

  1. 108

  2. 99

  3. 112

  4. 100
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The total weight increase is 12 * 0.75 = 9 kg. The new wrestler's weight is the old wrestler's weight plus the total increase: 90 + 9 = 99 kg.

Multiple choice

What is the average weight of Priya and Sony? Statement I: The average weight of Priya, Sony and Tina is 50 kg. Statement II: The average weight of Priya, Ritu and Sony is 48 kg. Statement III: The average weight of Ritu and Tina is 60 kg.

  1. I and II

  2. II and III

  3. I and III

  4. All I, II and III

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

P+S+T = 150. P+R+S = 144. R+T = 120. We have 3 equations with 4 variables. We need to find (P+S)/2. From 1 and 2, (P+S+T) - (P+S+R) = 150 - 144 = 6, so T-R = 6. Combined with R+T=120, we can solve for T and R. Then we can find P+S. All three statements are required.

Multiple choice

In a software company, there are 200 employees. Out of which, 140 are males having 150 as average marks in the interview. If the average marks of the all employees are 144, then what are the average marks of the female employees?

  1. 130

  2. 150

  3. 140

  4. 420

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total marks = 200 * 144 = 28800. Male marks = 140 * 150 = 21000. Female marks = 28800 - 21000 = 7800. Number of females = 200 - 140 = 60. Average female marks = 7800 / 60 = 130.

Multiple choice

Directions: The question given below is followed by two statements (A) and (B). You have to determine which statement(s) is/are sufficient/necessary to answer the question. Two groups of students X and Y took the same test. If the average score for group X was 68.2, then what was the average score for the combined group? (A) The average score for group Y was 73.5. (B) Group X had 20 more students than group Y.

  1. Statement (A) alone is sufficient, but statement (B) alone is not.

  2. Statement (B) alone is sufficient, but statement (A) alone is not.

  3. Both (A) and (B) together are sufficient, but none of them alone is sufficient.

  4. Both (A) and (B) together are not sufficient.
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice

The average weight of males in a family is 50 kg and the average weight of females in the same family is 40 kg. The average weight of the whole family is 42 kg. What could be the possible strength of males and females, respectively in the family?

  1. 2 and 8

  2. 2 and 10

  3. 3 and 9

  4. 4 and 12

  5. 4 and 15
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let M be the number of males and F be the number of females. (50M + 40F) / (M + F) = 42. 50M + 40F = 42M + 42F. 8M = 2F, so F = 4M. The ratio of males to females is 1:4. Option A (2 and 8) fits this ratio.

Multiple choice

The average age of a class of 50 students is 24 years. If the average age of 10 of them is 22 years while that of another 10 is 26 years, then what is the average age of the remaining 30 students?

  1. 23 years

  2. 25 years

  3. 24 years

  4. 28 years

  5. 22 years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total age = 50 * 24 = 1200. Age of 10 = 10 * 22 = 220. Age of another 10 = 10 * 26 = 260. Remaining 30 students total age = 1200 - 220 - 260 = 720. Average = 720 / 30 = 24.