Question

Of the four numbers whose average is 91, the first is 3/10 times the sum of other three. The first number is:

A) 126 B) 56 C) 168 D) 84

Answer 1

Let the first number be x.

x = (3/10) × (sum of other three sides)

Therefore, sum of other three sides = (10/3) × x

Average = Sum of four sides/4

Average = (x + sum of other three sides)/4

Therefore, Average = (x + 10x/3)/4

Since average = 91

91 = (13x/3)/4

x = (91 × 12)/13

x = 84

Therefore, the first number is 84.