SAT Math Question of the Day

Math Category: Algebraic Sets:

Q: Everyone in Ms. Levitt's class of 14 students has an iPhone or an Android or both. 8 students have the iPhone, while 9 students have the Android. How many have the iPhone, but not the Android?

UNANSWERED.

The correct answer is E.

A: 5 is the right answer.

Let's make a chart to figure out this set problem. There are 14 students, so make the chart 14 columns wide:

1	2	3	4	5	6	7	8	9	10	11	12	13	14

Next fill in the 8 with the iPhone:

1	2	3	4	5	6	7	8	9	10	11	12	13	14
i	i	i	i	i	i	i	i

Next fill in the 9 with the Android. Remember, in this problem, every student has an iPhone, Android, or both. This means we have to fill out the blank squares on the right first, so that every student is assigned something.

1	2	3	4	5	6	7	8	9	10	11	12	13	14
i	i	i	i	i	i	i	i
					A	A	A	A	A	A	A	A	A

Now we have filled out the chart with all the information we know. Looking at the chart we see that students #1 - #5 have the iPhone, but not the Android, so the answer is 5 students.