Question

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

Answer 1

Let the 4 numbers be: a, b, c & d  

As given a = (1/4)(b + c +d); ==> b + c + d = 4a ------ (1)  

Average of 4 numbers is given = 60  

==> Their sum a + b + c + d = 4*60 = 240 ------ (2)  

Substituting b + c + d = 4a from (1) in (2),  

a + 4a = 240  

Solving a = 48  

Thus the first number is = 48