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

The average age of 10 persons in a committee decreases by 2 years when two men aged 33 years and 37 years are substituted by two younger men. Find the average age of these two younger men.

  1. 29

  2. 28

  3. 24

  4. 25

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

The total age decrease is 10 * 2 = 20 years. The sum of the ages of the two men replaced is 33 + 37 = 70. The sum of the ages of the two new men is 70 - 20 = 50. Their average age is 50 / 2 = 25.

Multiple choice

The average of six numbers is 3.95. If the average of two numbers is 3.4 and that of the other two is 3.85, then find the average of the remaining two numbers.

  1. 4.8

  2. 4.7

  3. 4.6

  4. 4.5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The sum of 6 numbers is 6 * 3.95 = 23.7. The sum of the first two is 2 * 3.4 = 6.8, and the sum of the next two is 2 * 3.85 = 7.7. The sum of the remaining two is 23.7 - (6.8 + 7.7) = 23.7 - 14.5 = 9.2, so their average is 9.2 / 2 = 4.6.

Multiple choice

The average age of a class of 25 boys is 15 years 4 months. The average of the first 9 boys is 16 years 4 months and that of the next 13 boys is 14 years one month. Find the average age of the remaining three.

  1. 16 years

  2. 17 years 9 months

  3. 18 years 11 months

  4. 12 years

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

Total age = 25 * (15 + 4/12) = 25 * 15.333 = 383.33 years. First 9: 9 * (16 + 4/12) = 9 * 16.333 = 147 years. Next 13: 13 * (14 + 1/12) = 13 * 14.0833 = 183.0833 years. Remaining 3: 383.33 - 147 - 183.0833 = 53.25 years. Average = 53.25 / 3 = 17.75 years, which is 17 years 9 months.

Multiple choice

In an exam, the average score of the candidates was found to be 60. After deducting computational errors, the scores of 100 candidates had to be changed from 80 to 50 each, and the overall average score of students had to be reduced by 10. What was the total number of students in the class?

  1. 300

  2. 400

  3. 500

  4. 600

  5. 800
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let N be the number of students. Initial sum = 60N. New sum = 60N - 100*(80-50) = 60N - 3000. New average = (60N - 3000)/N = 60 - 10 = 50. 60N - 3000 = 50N, so 10N = 3000, N = 300.