Question

A group of 20 people has the oldest person with 90 years of age. The average of the group is reduced by 4, if the oldest person is reduced by someone new, Find the age of the new person.
80 years
60 years
30 years
10 years

Answer 1

then the answer is 30 years

Answer 2

Answer:

10 years

Step-by-step explanation:

let sum of people be X and average Be Y then

X/20 = Y ; X = 20Y

Now, person with 90 years age is replaced with someone new

let age of someone new is Z and new average be Y - 4

so,

(X - 90 + Z )/20 = Y - 4

X - 90 + Z = 20Y - 80

putting X = 20Y

20Y - 90 + Z = 20Y - 80

-90 + Z = -80

Z = 10