Question

10,4,7
The above set 4 numbers have a mean of 8
what could the mystery number

Answer 1

The mystery number is 11

Explanation:

→ Set up an equation

( 10 + 4 + 7 + x ) ÷ 4 = 8

→ Multiply both sides by 4

21 + x = 32

→ Minus 21 from both sides

x = 11

Answer 2

11 is the mystery number