Question

Aldo's scores on four tests are 88, 85, 100, and 86. What must the score be on the fifth test for her average to be 90?

Answer 1

aldo must score a 91 for it to average to a 90

Answer 2

x=5th test score

(88+85+100+86+x)/5=90

(359+x)/5=90

71.8+x/5=90

-71.8              -71.8

x/5=18.2

*5       *5

x=91

the fith test score has to be 91 in order for the average to be 90