Question

The manager is checking the results of the customer satisfaction surveys. The ones he has looked at have scores of 79%, 92%, 71%, and 86%. What score must be on the next survey to have a mean average of exactly 85% for the five surveys?

Answer 1

97%

Explanation:

for such a question we can use the percentage numbers like real unit numbers, as we need to analyze just the percentage numbers and align them with another percentage number with the result of another percentage number.

so, we just use the percentage numbers and deal with mean values and such like with real unit numbers.

therefore we need to find x

(79 + 92 + 71 + 86 + x) / 5 = 85

as the sum of all numbers divided by the number of measurements is the mean value.

and so,

79 + 92 + 71 + 86 + x = 425

328 + x = 425

x = 97

so, the next site must be 97%, so that the average for the 5 surveys will be exactly 85%