SOLUTION: Kate took a test and she got a grade between 80% and 95%, inclusive. What is the greatest percent error she could have?

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Question 1025395: Kate took a test and she got a grade between 80% and 95%, inclusive. What is the greatest percent error she could have?
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
A fifth grader would tell yoy that obviously, if kates right answers were 80% or more,
she had at most %22100%25%22-%2280%25%22=%2220%25%22 errors,
but to "show your work", you have to pretend it is not obvious,
and write some inequalities.
R= right answers (as percent of total questions/points)
W=%22100%25%22-R= wrong answers (as percent)
Since %2280%25%22%3C=R%3C=%2295%25%22
-%2280%25%22%3E=-R%3E=-%2295%25%22 (the %22%3C%22 signs are flipped because we are multiplying times -1 every expression related b those signs)
%22100%25%22-%2280%25%22%3E=%22100%25%22-R%3E=%22100%25%22-%2295%25%22
%2220%25%22%3E=W%3E=%2215%25%22
W%3C=highlight%28%2220%25%22%29 .
Kate's percent error was at most highlight%28%2220%25%22%29 .