SOLUTION: A student would like to have an average grade of 90 for 4 exams. His first 3 tests were 88, 79 and 94. What does he have to get on his 4th exam to get that 90 average? X is suppose

Algebra ->  Average -> SOLUTION: A student would like to have an average grade of 90 for 4 exams. His first 3 tests were 88, 79 and 94. What does he have to get on his 4th exam to get that 90 average? X is suppose      Log On


   

Question 286457: A student would like to have an average grade of 90 for 4 exams. His first 3 tests were 88, 79 and 94. What does he have to get on his 4th exam to get that 90 average? X is supposed to be the student's 4th exam score.
Answer by texttutoring(324) About Me  (Show Source):
You can put this solution on YOUR website!
Let s1=score 1, s2=score 2, s3=score 3, and x=the unknown score
The formula for average is:
Avg = (s1+s2+s3+x)/4
90= (88+79+94+x)/4
360=261+x
x=99
He would have to get 99 on his 4th exam in order to get 90 average.