MathRevolution wrote:

[GMAT math practice question]

When you buy a wrap from a certain store, you must select at least one of the three kinds of meat (beef, pork and fish), and one of lettuce, spinach and cucumber. You can also add one of oriental sauce, spicy mayo and sesame soy sauce. How many kinds of wraps can you buy?

A. 6

B. 9

C. 12

D. 18

E. 27

Question says you must select

at least one of 3 meats, which means you can select 1 meat or 2 or 3. Question also says that you

can (not must) add one sauce, which means you can add 0 sauce or 1 sauce.

Number of ways to select 1 meat: 3C3 = 3

Number of ways to select 2 meats: 3C2 = 3

Number of ways to select 3 meats: 3C3 = 1

Total number of ways to select meat = 3+3+1 = 7

Number of ways to select 1 veggie: 3

Number of ways to select 0 sauce OR 1 sauce: 1+3 = 4

# of different wraps = (Total number of ways to select meat) * (Number of ways to select 1 veggie) * (Number of ways to select 0 sauce OR 1 sauce) = 7*3*4=84