Question

The test scores of Clara are 68, 86, 76, x, 90. Which of the following gives the value of x, if the mean is 80?

• A. 70
• B. 80
• C. 82
• D. 72

Answer 1

The correct option is B 80

The test scores of Clara are

68, 86, 76, x, 90

It is given that, the mean of the data set is 80.

The mean of the data set is the sum of the data divided by the number of data values

Mean = $\frac{\text{sum of all data}}{\text{Number of data values}}$

Number of data values = 5

Therefore,

$80$ = $\frac{68+86+76+x+90}{5}$

$80$ =$\frac{320+x}{5}$

$⟹$ 320 + x = 5 $\times$ 80

$⟹$ 320 + x = 400

$⟹$ x = 400 - 320

$⟹$ x = 80

Hence, the value of x = 80.