SOLUTION: Please help me solve this question Miguel has scored 78,81,86,70,and 66 on his previous five tests. What score does he need on his next test so that his average (mean) is 76? I

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Question 1057994: Please help me solve this question
Miguel has scored 78,81,86,70,and 66 on his previous five tests. What score does he need on his next test so that his average (mean) is 76?
I have done several questions using the same equation which is 76*6=456 then I added the sum of all of the grades which is 315 then I subtracted 456-315=141 but when I submit it it says the answer is wrong.
Found 2 solutions by solve_for_x, josmiceli:
Answer by solve_for_x(190) About Me  (Show Source):
You can put this solution on YOUR website!
You are on the right track, but you missed a score when adding the grades he has received:

78 + 81 + 86 + 70 + 66 = 381

So he needs 456 - 381 = 75 on the next test.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = the score he needs on his next test
so the average is +76+
-------------------------
+%28+78+%2B+81+%2B+86+%2B+70+%2B+66+%2B+x+%29+%2F+6+=+76+
+%28+381+%2B+x+%29+%2F+6+=+76+
+381+%2B+x+=+456+
+x+=+456+-+381+
+x+=+75+
He needs 75 on the next test
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Looks like you just added up the test scores wrong
I did it 3 times and got +381+ each time