GWD7-25

jojof5460

Q25:

The buyer of a new home must choose 2 of 4 types of flooring and 2 of 6 paint colors. How many different combinations of type of flooring and paint color are available to the home buyer?

A. 4

B. 24

C. 48

D. 90

E. 96Answer: D

就只要C(2,4)*C(2,6)就可以了么？ 我怎么觉得还要乘4，因为这四种选出来后两两得再搭配

fhhrewr

if we have to pick 1 of 2 apples and 1 of 2 oranges, how many combinations are there?

so c(2, 1) * c(2, 1) = 4 ((1, 1), (1, 2), (2, 1), (2, 2)); u do have to consider all the combos. between the two pairs, but the product of the two covers all the possible combinations.

mjiirggh

不同意楼上的说法，这题出的不严谨，如果允许地板漆同样的颜色，理应的答案是90x4；如果两个地板必须漆不同颜色，则答案为90x2. Tiger的例子举的不妥--> 1) one of two 不同于two of mutiple; 2) 地板和色彩的关系不同于苹果和橙子的关系，除非苹果和橙子可以混合成果汁

正确的算法应该为:C(2,4) x C(2,6) x P(2,2) 或 C(2,4) x C(2,6) x [C(1,2) + P(2,2)]

举个最简单的例子，两块质量不同但无色的地板(a,b)，两种截然不同的颜色(x,y)，有几种装修方法？--> 两种(ax,by) + (ay,bx)