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In a class in which the final course grade depends entirely on the average of four equally weighted 100-point tests, Paul has scored 75, 80, and 91 on the first three. What range of scores on the fourth test will give Paul a C for the semester (an average between 70 and 79, inclusive)? Assume that all test scores have a non-negative value.

User JMGM
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1 Answer

3 votes

Answer:

Scores between 34 and 70 on the fourth test will give Paul a C for the semester.

Explanation:

The average is given by the sum of all scores divided by the number of scores.

In this question:

Sum of all scores: 75 + 80 + 91 + x = 246 + x

Number of tests : 4

Grade of 70:


(246 + x)/(4) = 70


246 + x = 280


x = 280 - 246


x = 34

Grade of 79:


(246 + x)/(4) = 79


246 + x = 316


x = 316 - 246


x = 70

Scores between 34 and 70 on the fourth test will give Paul a C for the semester.

User Flpn
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