SOLUTION: If Madeline scores 97% on her next math test, her average will be 90%. If she scores 73%, her average will be 87%. How many tests has Madeline already taken? a) 6 b) 7 c) 8 d) 9 e

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Question 251677: If Madeline scores 97% on her next math test, her average will be 90%. If she scores 73%, her average will be 87%. How many tests has Madeline already taken?
a) 6 b) 7 c) 8 d) 9 e) none of these
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!

let n= tests already taken
a=previous average
(97+n*a)/(n+1)=90
(73+n*a)/(n+1)=87
b)7
previous average was 89
check
(97+(7*89))/8=90
(97+623)/8
720/8=90
90=90
(73+(7*89))/8=87
(73+623)/8=87
696/8=87
87=87