Question

The average of four numbers is 28. if the average of first three of them is twice the fourth number, then the fourth number is

Answer 1

Hey,
Thanks for asking this question.

Lets suppose that four such numbers are a,b,c,d

=> (a+b+c+d)/4 = 28
=> (a+b+c)/4 + d/4 = 28
=> (a+b+c)/4 = (28 - d/4)
=> (a+b+c) = 112 - d

But according to the question,

(a+b+c)/3 = 2d
=> (a+b+c) = 6d

So taking value of a+b+c from both equations,

6d = 112 - d
=> d = 16

So the fourth number is 16.


●Hope my answer helped.