SOLUTION: A student received scores of 86, 76, and 90 on three quizzes, what is the lowest score the student can get on the next test to achieve an average score of at least 70?

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Question 1171981: A student received scores of 86, 76, and 90 on three quizzes, what is the lowest score the student can get on the next test to achieve an average score of at least 70?
Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.

Let x be the unknown value under the problem's question.


Then the average score is  %2886%2B76%2B90%2Bx%29%2F4.


So, you have this inequality

    %2886%2B76%2B90%2Bx%29%2F4 >= 70


to find x.


Multiply both sides by 4 and then simplify

    86 + 76 + 90 + x >= 280

    252 + x          >= 280

          x          >= 280 - 252 

          x          >=  28..


ANSWER.  The fourth score must be at least 28.

Solved, answered and explained. And completed.

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