裸跑请教一道PREP数学

ric_ye

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 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 colors.  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

谢谢!

答案是C

landroamer

2*4+2*C(4,3)=16

iamliz

尺寸相同颜色不同 = 尺寸二选一 C21 * 颜色四选三 C43 = 2 * 4 = 8

尺寸相同颜色相同 = 尺寸二选一 C21 * 颜色四选一 C41 = 2 * 4 = 8

加一起16种可能性。

KevinJM

楼上解答都对。发现其实数学题的计算原理都很简单，但是读题总是很绕——努力中