2007 AMC 12B Problem 12

A teacher gave a test to a class in which

10\%

of the students are juniors and

90\%

are seniors. The average score on the test was

84.

The juniors all received the same score, and the average score of the seniors was

83.

What score did each of the juniors receive on the test?

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Solution

Take a class of

10

students, so there is

1

junior and

9

seniors. The total of all scores is

10\cdot84=840,

and the seniors contribute

9\cdot83=747.

So the junior scored

840-747=93.

Thus, the correct answer is C.

Tagged: mean · percentage