A certain office supply store stocks 2 sizes of self-stick notepads, each in 4 colors: Blue, Green, Yellow Or Pink. The store packs the notepads in pacakages that contain either 3 notepads of the same size and the same color or 3 notepads of the same size and of 3 different colors. If the order in which teh colors are packed is not considered, how many different packages of the types described above are possible?

A) 6
B) 8
C) 16
D) 24
E) 32

Can you please show how you arrived at the answer choice C?

Thank you

Source: GMATPowerPrep(TM) - Practice Test 1

Category 1: consider all the possibilities that will give a same size (2 ways) and same color (4 ways) package. There are 2 packages and 4 colors => 8 different packages.

Category 2: consider all the possibilities for a same size but three different color package. Since you have four colors to choose from, you can use the combination formula to find how many ways to choose 3 from 4 colors. This will give you 4 options, but since you have two sizes, you have total of 8 ways to package the notes in this category.

Finally, you add your two methods of packaging for a total of 16 ways to package the notes. The correct answer is C.

Guest, thanks for the explanation. I like your style!

-dan