Question

The mean of the data is 18. What number is missing? 21,11,_,27,22,13,16

Answer 1

The missing number is 16

Solution:

Given that mean of data is 18

Let "x" be the missing number

The data set is:

21, 11, x , 27, 22, 13, 16

Sum of data set = 21 + 11 + x + 27 + 22 + 13 + 16

Sum of data set = 110 + x

The mean is given by formula:

$Mean = \frac{\text{sum of all numbers}}{\text{total numbers in data set}}$

Substituting the values we get,

$18 = \frac{110+x}{7}\\\\126 = 110 + x\\\\x = 126 - 110\\\\x = 16$

Thus the missing number is 16