Question

Rob's first four test scores are 80, 85, 100 and 85. What does he have to score on the last test in order to have a test average of 90?

Answer 1

Answer:

100

Step-by-step explanation:

85 +80+100+85+x(the unknown),/the number of numbers ie 5

350+x/5=90

350+x=90 * 5

350+x=450

x=450-350

x=100