### Home > MC1 > Chapter 2 > Lesson 2.2.3 > Problem 2-79

Armando has an A average for his first three test scores. His percentages on these tests were

What is the mean of his three scores?

The mean is

. Remember to show your work! Armando was absent for the fourth test, so he has a

on it until he takes it. His teacher has included the as part of his weekly progress report. What is the mean for the four test scores and ? Geanna did it this way:

Then she dividedby three because Armando only took tests. Joey reminded her that she still has to include the when she divides because it is the average of Armando's scores, not the average of the tests he has taken.

Using Joey's logic, what is Armando's new mean?Since Armando was doing so well before missing the test, he thinks that just one missing test will not hurt his grade very much. Write him a short note

**explaining**the effect that this one zero has on his grade.Tell him how many percentage points his average will drop.