Answer:
88%
Step-by-step explanation:
First we multiply the mean by 5.
77.4 x 5 = 387
Then we add all of the test scores.
88 + 77 + 70 + 72 = 299
We subtract the total of the scores from 387, which we got from mulitplying the mean by 5.
387 - 299 = 88
Therefore, Tom's score on his fifth test was an 88%.
Hope this helps!