Lisa is currently taking physics as one of her electives in school. Her grade at the end of the year is determined by the average of four exams, each worth 100 points. On her first test she got an 84, on her second she got a 92, and on her third an 80. What must she score on her fourth exam to get a B (80%) in the course?

A60
B64
C84
D85

If four tests average 80%, then the four scores must
add up to (4 x 80) = 320.

From the first three tests, she already has (84 + 92 + 80) = 256.

On the fourth one, anything over (320 - 256) = 64% will give her
an average of 80% for all four tests.

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adefioyelaoye adefioyelaoye · Answer 2 · 2022-04-20T11:26:33-04:00

She must score above 64 percent on her fourth exam to get a B (80%) in the course.

What is Average?

This is a mathematical term which is calculated by adding quantities together and dividing the total by the number of quantities.

To get four tests average to be 80%, then the four scores must

add up = 4 x 80 = 320.

The first three tests = (84 + 92 + 80) = 256.

On the fourth one, anything over (320 - 256) = 64%

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