Question

Brad's average for five quizzes is 86If he wants to have an average of 88for six quizzes, what is the lowestscore he can receive on his sixth quiz?

Answer 1

SOLUTION

Let the sum of Brad's quizzes score be x.

Since

$\text{average = }\frac{s\text{um of quiz scores }}{n\text{umber of quizzes}}$

It means that

$\begin{gathered} 86=\frac{x}{5} \\ \text{for five quizzes } \end{gathered}$

Let the score of the sixth quiz be y, so this means that

$88=\frac{x+y}{6}$

From the first equation, we have x as

$\begin{gathered} 86=\frac{x}{5} \\ \text{cross multiply, we have } \\ x=86\times5 \\ x=430 \end{gathered}$

Now we will substitute x for 430 into the second equation, we have

$\begin{gathered} 88=\frac{x+y}{6} \\ 88=\frac{430+y}{6} \\ \text{cross multiply, we have } \\ 430+y=88\times6 \\ 430+y=528 \\ \text{collecting like terms, y becomes } \\ y=528-430 \\ y=98 \end{gathered}$

Hence the answer is 98