SAT Math Question of the Day

Math Category: Algebraic Sets:

Q: In a group of 12 Juniors, 5 are in Math Club, 8 are in Leo Club, and 4 are in both Math Club and Leo Club. How many are not in either club?

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

UNANSWERED.

The correct answer is C.

A: 3 is the right answer.

Let's make a chart to figure out this set problem. There are 12 Juniors, so make the chart 12 columns wide:

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

Next fill in the 5 from Math Club:
1 2  3 4  5 6  7 8  9 10  11 12 
MCMC MCMC MC          
                 

Next fill in the 8 in Leo Club. Remember that 4 are in both Math Club and Leo Club, so let's say it's Juniors #1, #2, #3, and #4:
1 2  3 4  5 6  7 8  9 10  11 12 
MCMC MCMC MC          
LCLC LCLC  LC LCLC LC    

Now we have filled out the chart with all the information we know. Looking at the chart we see that Juniors #10, #11, and #12 are in neither club, so the answer is 3.