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If you receive an 80%, 75% , 70% and 82% in four math tests, what grade do you need to on the fifth test to average an 80% in the course.Remember to set up the linear equation and solve.

User Keene
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6.5k points

1 Answer

6 votes

remember the average formula


\bar{x}=(\sum ^(\infty)_(n\mathop=0)xi)/(n)

in this case n= total number of data and xi is each of the data

to solve this problem you know that you did a total of 5 tests and have the average and you are missing one of them, it should look like this when replacing


80=(80+75+70+82+x)/(5)

clear the equation to find x, like so


\begin{gathered} 80\cdot5=80+75+70+82+x \\ 400=80+75+70+82+x \\ x=400-80-75-70-82 \\ x=93 \end{gathered}

You must score a 93% to obtain a 80%average on the course

User Strange
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6.2k points
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