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Jim has received scores of75and81on his first two 100 point tests.What score must he get on his third 100 point test to keep an average of84or greater?

User Skatch
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1 Answer

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start writing the corresponding equation using the corresponding formula for the average grade


\begin{gathered} \bar{x}=(x_1+x_2+x_3)/(3) \\ \text{then, } \\ 84=(75+81+x_3)/(3) \\ 84=(156+x_3)/(3) \end{gathered}

solve the equation


\begin{gathered} 84\cdot3=156+x_3 \\ 252=156+x_3 \\ 252-156=x_3 \\ 96=x_3 \end{gathered}

He must get at least 96 points on his test to keep an average of 84

User Przemek
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