Question

average of 3 numbers is 28, first number is half of 2nd number and 3rd is twice of 2nd number, find 3rd number

Answer 1

hi

Average of 3 numbers is 28

x/3 = 28

x = 28*3

x = 84

now let a 2nd number be a

first number is half of 2nd number

1st number = 1a/2

3rd is  twice 2nd

= 3rd = 2a

so 

2a + a + 1a/2 / 3 = 28

2a + a + 1a/2 = 84

3a +1a/2 = 84

6a +1a/2 = 84

7a/2 = 84

a = 84*2/7

a = 12*2

a = 24

since 3rd number is 2a

=>2*24

=>48

hope it helps u

:)

Answer 2

Let the second number be x.
First number is half of second number
Therefore first number = x/2
Third number is twice of second number
Therefore Third number = 2x

The average of the three numbers = 28
Therefore
(x + x/2 + 2x)/3 = 28
((2x + x + 4x)/2)/3 = 28
7x/2 * 1/3 = 28
7x/6 = 28
7x = 28*6
x = 168/7
x = 24

Therefore second number is 24
Third number = 2x = 48.

Hope this helps you.