Desiree's test score are 77,90,66 and 82.what score does she need on the last test in order to average 80 on her tests ?

3 answers

500 * .8 = 400

77 + 90 + 66 + 82 = 315

400 - 315 = 85 needed on next test
mean = ∑x/n

80 = (77+90+66+82+x)/5

Solve for x.
Lakita's test scores are 77, 86, 66, and 80. What score does she need on the last test in order to average 80 on her tests?