SOLUTION: If Sarah scored an 80,95,75 and an 90 on her first four test , what must she score on her fifth test if she wants An average of 88?

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: If Sarah scored an 80,95,75 and an 90 on her first four test , what must she score on her fifth test if she wants An average of 88?       Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 1143128: If Sarah scored an 80,95,75 and an 90 on her first four test , what must she score on her fifth test if she wants An average of 88?
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52787) About Me  (Show Source):
You can put this solution on YOUR website!
.
%28%2880%2B95%2B75%2B90%29+%2B+x%29%2F5 = 88,


80 + 95 + 75 + 90 + x = 5*88


x = 5*88 - (80 + 95 + 75 + 90)


x = 100.     ANSWER


CHECK.   %2880+%2B+95+%2B+75+%2B+90+%2B+100%29%2F5 = 88.


Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Here is a way that you might find faster and easier when working a problem like this involving the average of numbers that are "close together".

Comparing each score to the desired average of 88...
80-88 =  -8
95-88 =  +7
75-88 = -13
90-88 =  +2
      -----
        -12

Overall, her current point total is 12 points below the desired average; that means her next test must be 12 points above the desired average.

ANSWER: She needs a score of 88+12 = 100 on the next test to get an average of 88.