Question

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?

Answer 1

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