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Isabella must take four $100$-point tests in her math class. Her goal is to achieve an average grade of $95$ on the tests. Her first two test scores were $97$ and $91$. After seeing her score on the third test, she realized she can still reach her goal. What is the lowest possible score she would have made on the third test? 
Overseas Competition->Knowledge Point->Word Problem Modules->Average Problems 
Isabella wants an average grade of $95$ on her $4$ test; this also means that she wants the sum of her test scores to be at least $95\times 4=380$ (if she goes over this number, she\textquotesingle ll be over the goal!). She\textquotesingle s already taken two tests, which sum to $97+91=188$, which means she needs $380-188=192$ more points to achieve her desired average. In order to minimize the score on the third test, we assume that Isabella will receive all $100$ points on the fourth test. Therefore, the lowest score on the third test would be $192-100=92$. 