SOLUTION: Question Help Going into the final​ exam, which will count as two​ tests, Amelia has test scores of 75,80,70,65, and 92.  What score does Amelia need on the final in ord

Algebra ->  Percentages: Solvers, Trainers, Word Problems and pie charts -> SOLUTION: Question Help Going into the final​ exam, which will count as two​ tests, Amelia has test scores of 75,80,70,65, and 92.  What score does Amelia need on the final in ord      Log On


   

Question 1143764: Question Help
Going into the final​ exam, which will count as two​ tests, Amelia has test scores of 75,80,70,65, and 92.  What score does Amelia need on the final in order to have an average score of​ 80?
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.

The governing equation is


    %28%2875%2B80%2B70%2B65%2B92%29%2B2x%29%2F%285%2B2%29 = 80.


Simplify and solve for x, which is the unknown value under the question.


    x = %287%2A80+-+%2875+%2B+80+%2B+70+%2B65+%2B92%29%29%2F2 = 89.    ANSWER


Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


Here is an alternative method for solving a problem like this involving the average of numbers that are close together.

Compare the given numbers to the desired average to see how far above or below the desired average the current tests are:
75:  -5
80:   0
70: -10
65: -15
92: +12
   -----
    -18

Overall, the current test scores are 18 points below the desired average; the score on the final has to make up those 18 points. Since the final counts as two tests, the score on the final must be 18/2 = 9 points above the desired average.

ANSWER: 80+9 = 89