SOLUTION: a student is suppose to subtract 15 from a certain number but mistakenly added 25 and the result is 145.find the percentage error.

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Question 1097158: a student is suppose to subtract 15 from a certain number but mistakenly added 25 and the result is 145.find the percentage error.
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
x=the initial number
x-15= the intended result
x%2B25= the result of the mistaken calculation

We know that x%2B25=145 , so we solve to find x :
x%2B25-25=145-25
x=120 .
So, x-15=120-15 , and x-15=105 was the intended result.
The miscalculated result is off by 145-105=40 .
As a fraction/percentage of the intended result, that amounts to
40%2F105=8%2F21= approximately0.38095=38.095%2F100=%2238.095%25%22 .
So,
highlight%28%2238%25%22%29 or highlight%28%2238.1%25%22%29 is a reasonable answer.