Question

The mean of four numbers is 7. Three of the numbers are 5,7 and 7. What is the fourth number?

Answer 1

9 is the fourth number.

Explanation:

9 is the fourth number because 7(mean) x 4(amount of numbers) = 28 and 7 plus 7 plus 5 plus 9 equals 28 so when you divide you get 7.

Answer 2

fourth number is 9

Explanation:

let 'x' equal the fourth number

(5+7+7+x)/4 = 7

cross-multiply to get:

19 + x = 28

x = 9