Question

There are four numbers. Average of the first three is 15 and of last three is 16. If the last number is 19, find the first number?

Answer 1

Answer:

22

Step-by-step explanation:

four no are A , B ,C , D

we have D=19

and also A+B+C/3=15

Therefore A+B+C=45.............(1)

also we have

B+C+D/3=16

B+C+19=48...............(2)

substract eqn 1and 2

tgen we get -A-19=-3

A=22

Answer 2

Answer:

Let the no. Be x, y, z,19

Acc. To. question

X+y+z/3=15 and y+z+19/3=16

So y+z=16*3-19

Y+z=29

Now

X+29/3=15

So x=16 ans