Question

A poll asks shoppers at the mall how many cups of water they typically drink in a day. The results of the poll are listed below.

Answer 1

6
is the first quartile

Answer 2

First you find the median, the middle term (if there are an even number of terms it is the average of the middle two terms.)  Since you have 21 terms, odd, you just use the middle term, in this case 8.  The first quartile works the same way, but just on the left half between the start and the median...so the first quartile is 6.