An ice cream parlor has 30 flavors but Su likes only half of them. It isn't because she's picky. This parlor features the flavors Charred Chocolate Chip, Swine Swirl and Deuce de Leche. It doesn't actually do a lot of business.
If the scooper makes a three-scoop ice cream cone at random (using three different flavors),
(a) What is the probability Su will like all three flavors?
(b) What is the probability Su will like at least one flavor?
Answer
(a) The probability Su likes all three flavors is the probability that all three scoops were chosen from the 15 Su likes.

(b) The probability Su likes at least one flavor is
1 – (probability Su likes none of the flavors).
The probability Su likes none of the flavors is the probability that all 3 scoops were chosen from the 15 Su doesn't like. This probability is the same as the probability that Su likes all the flavors.

The probability that Su likes at least one flavor is
.