notepads - gmatprep

arocks · Posted: Fri Oct 12, 2007 9:06 am Post subject: notepads - gmatprep

A certain office supply store stocks 2 sizes of notepads, each in 4 colors: blue, green, yellow, or pink. The store packs the notepads in packages that contain either 3 notepads of the same size and the same color or 3 notepads of the same size and of 3 different color. If the order in which the 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

OA - C

Please explain. Thanks.

Suyog · Posted: Fri Oct 12, 2007 11:18 am Post subject:

let sizes be A and B

same size and the same color, For Size A
count = 4 ( Size A and color Blue, Green, yellow, Pink)
same size and the same color, For Size B
count = 4

Total = 8

same size and of 3 different color, For size A
4C3
count = 4
same size and of 3 different color, For size B
4C3
count = 4

Total = 8

Different packages = 8 + 8 = 16

Ans C