Question

Kai is a struggling student who has received the following grades on his quizzes: 75, 80, 70, 40, 94, 76, 82, and 74. His teacher allows for students to drop their lowest quiz grade, but only if they are also willing to drop their highest quiz grade in exchange. Would it be best for Kai to take his teacher up on this offer or should he take his grade he currently has? Why is your choice the better option?

Answer 1

First find the average of his quizzes right now.

$\frac{ 75+80+70+40+94+76+82+74}{8}$

This is just the sum of his quiz scores divided by the number of quiz scores

You should get 73.875

Now we need to find the average of his quiz scores once the lowest and highest scores are dropped and not included.

lowest score = 40
highest score = 94

Take the sum of his quizzes without 40 and 94.

$\frac{75+80+70+76+82+74}{6}$

(Remember that we're divided by 6 and not 8 because we dropped two scores, so the total number of quizzes is two less)

Once we simplify this, we should get roughly 76.167

Compare the two scores:
original = 73.875
new = 76.167

Because the new average is higher, Kai should drop his highest and lowest scores. :)

You can also tell this because the lowest score is much lower from the average than the highest is higher from the average.