Math CentralQuandaries & Queries


Question from Raj, a student:

Harris has an 87 in a class where daily works count 20%,quizzes count 20% and tests count 60%.
If there are only two test scores what must the score on his second test to raise his average to 90?

Hi Raj,

This question is not well worded but I think the situation is this. The final grade is to be composed of daily work which counts 20%, quizzes which count 20% and two tests which count 30% each. You have completed everything except the final quiz and your score so far is 87%. What do you need to score on the final test to obtain a final grade of 90%?

The daily work, quizzes ad first tests contribute 70% to the final grade and the second test contributes 30%. Thus your final grade will be 70% of the 87 points you have already plus 30% of your score on the second test. Suppose you score $x$ on the second test then your final grade will be calculated by

\[0.7 \times 87 + 0.3 \times x.\]

What is $x$ if your final grade is 90?



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