Cracking The SAT Premium

10.Maria    has taken   four    chemistry   tests   and has an  average (arithmetic mean)   score   of  80. If

she scores  a   90  on  her fifth   chemistry   test,   what    is  her average for these   five    tests?

A) 80

B) 81

C) 82

D) 84

Mark    It!

Make    sure    you’re  drawing

a   new Average Pie each

time    you see the word

average in  a   question.

Here’s How to Crack It

Start by drawing an average pie and filling in what you know. You can put 4 in for the number of things
and 80 for the average. You can calculate that Maria has gotten 320 total points on her first four tests.
Your pie should look like this:

Now, draw another average pie and fill in what you know. This time, there are five tests. The question
wants to know the average, so you also need to fill the total. The total for all five tests is the total from the
first four tests plus the score from the fifth test: 320 + 90 = 410. Put that on the pie and divide to find the
average:

The answer is (C), 82.