2011 AMC 12B Problem 2

Josanna’s test scores to date are

90,

80,

70,

60,

and

85.

Her goal is to raise her test average at least

3

points with her next test. What is the minimum test score she would need to accomplish this goal?

Show solution

Solution

The five scores sum to

90+80+70+60+85=385,

giving an average of

77.

The goal is a new average of at least

80.

Six tests averaging

80

must total

6\cdot80=480,

so the sixth score must be at least

480-385=95.

Thus, the correct answer is E.

Tagged: mean