Average Question Types
In this article, we are going to have a look at the various types of questions that are framed in aptitude examinations from the chapter of average.
Type 1
Q. Average marks of 40 students in a class is 60. Average marks of 25 students out of them is 54. What must be the average marks of the remaining students?
(a) 65 (b) 70 (c) 72.5 (d) 57
Explanations :
Average marks of 40 students in a class is 60.
Hence, the total marks of 40 students = 40 × 60
Average marks of 25 students out of them is 54.
So, the total marks of 25 students = 25 × 54
Total marks of remaining 15 students = Total marks of 40 students - Total marks of 25 students = (40 × 60) – (25 × 54) = 2400 – 1350 = 1050
So, the average marks of the remaining 15 students = Total marks / Number of remaining students = 1050 / 15 = 70
Answer: (b)
Average marks of 40 students in a class is 60. Average marks of 25 students out of them is 54.
Difference between the average marks = 60 - 54 = 6
Total deficit in average marks due to 25 students = 6 × 25
This deficit has to be covered by the rest of the 40 - 25 = 15 students.
So, the marks above average that each of those 15 students need to score = (6 × 25)/15 = 10
So, the average marks of the remaining 15 students = Group Average + 10 = 60 + 10 = 70
Answer: (b)
Type 2
Q. There are two group of boys namely A and B with 45 and 55 boys respectively. In group A the tallest boy is 130 centimetres in height and the height of shortest boy is 120 centimetres. In group B height of the tallest boy is 180 centimetres and that of shortest boy is 140 centimetres. Two boys are shifted from Group-A to Group-B.
Consider the following statements:
- The average height of Group B will definitely decrease.
- The average height of Group A will definitely increase.
Which of the above statements is/are correct?
(a) 1 (b) 2 (c) Both (d) None
Explanation:
Average = Sum of observations / Number of observations
Since 2 students are moved from A to B, therefore average height of group B will definitely decrease. The new students must be having less height than the previous minimum height of Class B. Statement 1 is correct.
However, we cannot be sure regarding the heights of the 2 students that have been moved from group A. They may have height close to 130 cm, which will lead to decrease in the average height of group A. If they have height close to 120, it will lead to increase in the average height of group A. Therefore, we cannot determine whether average height of group A will increase or decrease. Statement 2 is incorrect.
Answer: (a)