Question

There are four numbers.Average of first 3 is 15 and that of last is 16.If the last numbers is 19.Find the first number

Answer 1

Answer:

16

Step-by-step explanation

Let us assume the four numbers as a,b,c,d

Given that:~

Average of 1st three numbers =(a+b+c)×1/3 = 15------(1)

Average of last three numbers =(b+c+d)×1/3 = 16------(2)

Last number is 19 (ie. d = 19)

Putting d = 19 in eq. (2)

=>> (b+c+19)×1/3 = 16

=>>(b+c+19) = 16×3

=>>(b+c+19) = 48

=>>b+c = 48-19 = 29

=>>b+c = 29 ----(3)

Substituting eq.(3) in eq.(1)

=>> (a+29)×1/3 = 15

=>> a+29 = 15×3

=>> a+29 = 45

=>> a = 45 - 29 = 16

=>> a = 16

Now the required number ie. first number = 16