SOLUTION: If my exam grades are 79, 93, 91, and 68, what grade would I need on my next exam to have an average of 80? I need to learn how to work this problem.

Algebra ->  Average -> SOLUTION: If my exam grades are 79, 93, 91, and 68, what grade would I need on my next exam to have an average of 80? I need to learn how to work this problem.      Log On


   

Question 702422: If my exam grades are 79, 93, 91, and 68, what grade would I need on my next exam to have an average of 80? I need to learn how to work this problem.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = next exam grade

Add up the grades, divide by 5 to average them, then set that equal to the desired average grade of 80

(79+93+91+68+x)/5 = 80

Now solve for x

(79+93+91+68+x)/5 = 80

79+93+91+68+x = 80*5

79+93+91+68+x = 400

331+x = 400

x = 400 - 331

x = 69

So you need a 69 on the next exam to get an average of 80. If you score higher than 69, then your average will be larger than 80.