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

In a Math test taken by $35$ students, the average score of $15$ girls is $10$ and that of $20$ boys is also $10$. Which of the following can be calculated based on the above data?

  1. The highest score in the class.

  2. The lowest score among the boys in the class.
  3. The sum of the scores of the $35$ students of the whole class.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Average = Sum / Count. Sum = Average * Count. Sum of girls = 15 * 10 = 150. Sum of boys = 20 * 10 = 200. Total sum = 350. This can be calculated.

Multiple choice

$16$ children are to be divided into two groups $A$ and $B$ of $10$ and $6$ children. The average percent marks obtained by the children of group $A$ is $75$ and the average percent marks of all the $16$ children is $76$. What is the average percent marks of children of group $B$?
  1. $77\cfrac{1}{3}$
  2. $77\cfrac{2}{3}$
  3. $78\cfrac{1}{3}$
  4. $78\cfrac{2}{3}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let x be the average marks of group B. The total marks of all 16 children is 16 * 76 = 1216. The total marks of group A is 10 * 75 = 750. The total marks of group B is 1216 - 750 = 466. The average for group B is 466 / 6 = 233 / 3 = 77 2/3.

Multiple choice

A person travels up hill at an average speed of (u - v) km/hr and comes down the hill back at an average speed of (u + v) km/hr. His average speed for the whole journey is ___________________.

  1. u km/hr
  2. $\displaystyle\frac{u^2-v^2}{u}\:km/hr$
  3. $\sqrt{u^2-v^2}\:km/hr$
  4. $\displaystyle\frac{u}{u^2-v^2}\:km/hr$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed = Total distance / Total time. Let distance of hill be d. Time up = d/(u-v), time down = d/(u+v). Total time = d/(u-v) + d/(u+v) = d(u+v+u-v)/(u^2-v^2) = 2du/(u^2-v^2). Average speed = 2d / (2du/(u^2-v^2)) = (u^2-v^2)/u.

Multiple choice

A high school musical production sells student tickets for $ $5$ each and adult tickets for $ $8$ each. If the ratio of adult to student tickets purchases is $3 : 1$, what is the average income per ticket sold?
  1. $ $5.50$
  2. $ $5.75$
  3. $ $6.50$
  4. $ $7.25$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For every 1 student ticket (cost 5), there are 3 adult tickets (cost 8). Total cost for 4 tickets is 5 + (3 * 8) = 29. Average income per ticket = 29 / 4 = 7.25.