Question 586453
Let x = the score Heather must get on the fifth test to obtain a mean of 85 on the five tests.
This means that the average (mean) of the five tests is to be 85, so we find the average of the five test scores in the usual way: The sum of the scores divided by the number of scores.
{{{(81+93+74+95+x)/5 = 85}}}
{{{(343+x)/5 = 85}}} Multiply both sides by 5.
{{{343+x = 425}}} Subtract 343.
{{{x = 82}}}
Heather will need to score 82 on her fifth test to get an overall average of 85 for the five tests.