SOLUTION: The day of a quiz, only Michelle was absent. The average grade of the other students was 85. When Michelle took a make-up quiz her grade was a 30 which lowered the class average to

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Question 644494: The day of a quiz, only Michelle was absent. The average grade of the other students was 85. When Michelle took a make-up quiz her grade was a 30 which lowered the class average to 80. How many students are in the class?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The day of a quiz, only Michelle was absent.
The average grade of the other students was 85.
When Michelle took a make-up quiz her grade was a 30 which lowered the class
average to 80. How many students are in the class?
:
Let n = number of students in the class (including Michelle)
:
We know that (n-1) students averaged 85, therefore the equation would be:
%2885%28n-1%29%2B30%29%2Fn = 80
multiply both sides by n
85(n-1) + 30 = 80n
85n - 85 + 30 = 80n
85n - 55 = 80n
85n - 80n = 55
5n = 55
n = 55/5
n = 11 students in the class
:
:
Check this, find the average
Av = %2885%2810%29%2B30%29%2F11
Av = 880/11
Av = 80