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Question 471026: A student having marks of 65 and 75 wishes to raise the average of the two marks and a test mark to 80. What must he receive on the test?
Answer by algebrahouse.com(1659)   (Show Source):
You can put this solution on YOUR website! Add the two given scores with the missing score, divide by 3, and that is the average. Assuming, everything is weighted the same.
65 + 75 + x
------------ = 80
3
140 + x
------- = 80 {combined like terms in numerator}
3
140 + x = 240 {multiplied both sides by 3}
x = 100 {subtracted 140 from both sides}
He must receive 100% on the test.
For more help from me, visit: www.algebrahouse.com
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