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

If John makes a contribution to a charity fund at school, the average contribution size will increase by 50%, reaching $75 per person. If there were 5 other contributions made before John`s, what is the size of his donation?
  1. $100
  2. $150
  3. $200
  4. $250
  5. $450
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the sum of the 5 previous contributions be S. The original average was S/5. The new average is (S + x) / 6 = 75, so S + x = 450. The new average is 1.5 * (S/5), so (S + x) / 6 = 1.5 * (S/5). Substituting S + x = 450: 450 / 6 = 75 = 1.5 * (S/5), so S/5 = 50, S = 250. Then x = 450 - 250 = 200.

Multiple choice

The given data shows the number of patients who consulted the doctors in a hospital during a month. What is the average number of patients consulted in a day? No. of patients No. of days 0 – 10 2 10 – 20 6 20 – 30 9 30 – 40 7 40 – 50 4 50 – 60 2 Total 30

  1. 13.0

  2. 19.6

  3. 22.9

  4. 28.7

  5. 24.0
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Calculate the midpoint of each class: 5, 15, 25, 35, 45, 55. Multiply by frequency: 5*2=10, 15*6=90, 25*9=225, 35*7=245, 45*4=180, 55*2=110. Sum = 860. Average = 860/30 = 28.66, which rounds to 28.7.

Multiple choice

Directions: The question below consists of a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statements are sufficient to answer the question. What is the exact average of n, 35, 39, 42, p and w? I. n is six more than w. II. w is four less than p.

  1. The data in statement I alone is sufficient to answer the question, while the data in statement II alone is not sufficient to answer the question.

  2. The data in statement II alone is sufficient to answer the question, while the data in statement I alone is not sufficient to answer the question.

  3. The data in statement I alone or in statement II alone is sufficient to answer the question.

  4. The data in both the statements I and II are not sufficient to answer the question.

  5. The data in both the statements I and II together are necessary to answer the question.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The average of n, 35, 39, 42, p, and w is (n + 35 + 39 + 42 + p + w) / 6. The statements provide relationships between n, w, and p (n = w + 6 and w = p - 4), but they do not provide the actual values for any of the variables. Therefore, the sum cannot be determined.

Multiple choice

There are 26 students in a class and one of them who is 14 years old leaves the class and his place is filled by a newcomer. If the average age thereby is lowered by one month, what is the age of the newcomer?

  1. 11 years and 10 months

  2. 12 years

  3. 11 years and 11 months

  4. 14 years

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

Total age decrease = 26 students * 1 month = 26 months = 2 years and 2 months. Newcomer age = 14 years - 2 years and 2 months = 11 years and 10 months.

Multiple choice

The average of two numbers increases by 20 when one of the numbers is doubled and it increases by 25 when the other number is doubled. What is the average of both numbers?

  1. 40

  2. 45

  3. 50

  4. Cannot be determined

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

Let the numbers be x and y. Average = (x+y)/2. If x is doubled: (2x+y)/2 - (x+y)/2 = 20 => x/2 = 20 => x = 40. If y is doubled: (x+2y)/2 - (x+y)/2 = 25 => y/2 = 25 => y = 50. Average = (40+50)/2 = 45.