The grades received on a test by twenty students were: 100, 55, 75, 80, 65, 85, 90, 80, 45, 40, 50, 85, 85, 80, 80, 70, 65, and 60. What is the average?

Answer 1

You seem to be missing two scores.

Find the missing scores. Add all of the scores together and divide by 20.