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

Directions: In the following problem, a question is followed by three statements I, II and III. Read the question and the statements carefully and choose which statements are required to answer the question. How many boys are there in the class? I. The number of boys is 20 more than the number of girls. II. The average weight of boys is 40 kg and that of girls is 30 kg. III. The average weight of all the students of the class is 36 kg.

  1. I and II only

  2. II and III only

  3. All I, II and III

  4. Either I and II, or II and III

  5. The question cannot be answered even using all the statements together.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let B be boys and G be girls. (I) B = G + 20. (II) Average weight of boys = 40, girls = 30. (III) Average weight of class = 36. The total weight is 40B + 30G = 36(B + G). This gives 40B + 30G = 36B + 36G, so 4B = 6G, or 2B = 3G. Combining with B = G + 20, we can solve for B and G. All three are needed.

Multiple choice

The average age of 8 members of a group is 36 years. The age of the eldest member is 32 years. If we exclude that eldest member from the group, then what will be the average age (in years) of the remaining members?

  1. 38.5 years

  2. 42.67 years

  3. 48.5 years

  4. 36.57 years
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The total age is 8 × 36 = 288 years. Removing the stated 32-year-old member leaves 256 years among 7 members, so the average is 256/7 = 36.57 years approximately. The wording is inconsistent because a 32-year-old cannot be the eldest when the group average is 36 years.