Question

Out of four numbers the average of first 3 is 16 and that of last three number is 15.If the last number is 18 the first number is

Answer 1

Answer:

First number = 21

Step-by-step explanation:

Let the four no.s be a,b,c and d.

Average of 1st three = 16

a+b+c / 3 = 16

a+b+c = 48 -------(1)

d = 18

Average of last 3 no.s = 15

b+c+d /3 = 15

b+c+d = 45

b+c = 45-18

b+c = 27 -----------(2)

Substituting (2) in (1) .

a+ 27 = 48

a = 48-27

a = 21

First number = 21