SOLUTION: the average mark of 4 tests is 72 if the numbers are 60 and 80 find the third number

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Question 316966: the average mark of 4 tests is 72 if the numbers are 60 and 80 find the third number
Answer by JBarnum(2146) About Me  (Show Source):
You can put this solution on YOUR website!
dont u mean 3 tests since theres clearly no indication to find the 4th one and with a 2nd variable it would make for an incredible guess and check question with lots of possibilities. so im going to assume u meant 3 tests
%2860%2B80%2Bx%29%2F3=72
%28140%2Bx%29%2F3=72
%28140%2Bx%29=216
x=76


just to show u what the problem would be with 2 unknowns:
%2860%2B80%2Bx%2By%29%2F4=72
%28140%2Bx%2By%29=288
%28x%2By%29=148
as u can se there are many possibilities for what x or y could be, which would make a question like this unanswerable.


good luck