Question

The average of four numbers is 38, and the average of the first two numbers is 42, and the average of the last three numbers is 36. What is the second number?

Answer 1

40

Explanation:

let the numbers be a+b+c+d.

the average of 4 numbers is 38

; (a+b+c+d)/4 = 38

(a+b+c+d) = 152 ......equ1

the average of the first two numbers is 42

; (a+b)/2 = 42

(a+b) = 84 ...... equ2

the average of the last three numbers is 36

; (b+c+d)/3 = 36

(b+c+d) = 108 .....equ3

substitute equ3 into equ1

a + 108 = 152

a= 152 - 108

a = 44

input the value of a into equ2

44 + b = 84

b = 40

the second number is 40.

I hope this helps.