The mean of 7 numbers is 10. Four of the numbers are 8, 5, 7 and −10. The remaining three numbers are each equal to k. Find k

Answer 1

(8 + 5 + 7 + (-10) + k + k + k) / 7 = 10

Can you solve for k and answer?

Answer 2

To find the mean, you find the sum of the digits, and then you divide by the number of digits. In this case, the sum of the digits is

8 + 5 + 7 + (-10) + k + k + k.

This can be simplified to:

10 + 3k

The number of digits is 7, and you know that the mean is 10. Therefore:

(10 + 3k) / 7 = 10

(10 + 3k) = 70

3k = 60

k = 20