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| Math Central | Quandaries & Queries |
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Question from janna, a student: After taking 4 quizes your average is 71 out of 100. what must your average on the next 5 quizes be to increase your average to an 81 out of 100? |
Hi Janna,
Suppose that S is the sum of your scores on the first 4 quizzes then S/4 = 71 so S = 4
71 = 284.
Suppose that the sum of your grades on the next 5 quizzes is T then the total of your grades on all 9 quizzes is S + T = 284 + T.
You want the average on all 9 quizzes to be 81 so (284 + T)/9 = 81.
Solve for T. What is your average on quizzes 5 to 9?
Penny
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