A group of 25 people has the oldest person with 90 years of age.
| A group of 25 people has the oldest person with 90 years of age. The average of the group is reduced by 3, if the oldest person is replaced by someone new, Find the age of the new person?
A. 60
B. 45
C. 30
D. 15
Please scroll down to see the correct answer and solution guide.
Right Answer is: D
SOLUTION
GIVEN:
A group of 25 people has the oldest person with 90 years of age.
FORMULA USED:
Average = Sum of numbers/Total numbers
CALCULATION:
Suppose age of new person = x years
Initial average of group = a
So,
(25a – 90 + x) = 25(a – 3)
⇒ (25a – 90 + x) = 25a – 75
⇒ x = 90 – 75 = 15
Hence, age of new person = 15 years
Difference between the age of the oldest and the newest member = 25 × 3 (because by this number the sum of ages of all the persons in the group has reduced) = 75 years
So,
Age of the new person = 90 – 75 = 15 years (One should be able to think like this directly and not solve such questions via the ‘x’ method as it is time consuming)
