Of the four numbers, whose average is 60, the first is one-fourth of the sum of the last three. The first number is :

A 17

B 29

C 36

D 48

Correct Answer: Option D

Let the first number be x,

Then, sum of the four numbers = x + 4x = 5x.

so, 5x/4 = 60 or x

=\(\frac{60\times4}5\)

= 48.