数学题求助

qiuqiaomm

 

Q31:

There are 5 cars to be displayed in 5 parking spaces with all the cars facing the same direction.  Of the 5 cars, 3 are red, 1 is blue, and 1 is yellow.  If the cars are identical except for color, how many different display arrangements of the 5 cars are possible?

 

A.    20

B.    25

C.    40

D.    60

                    E.    125

指点一下？

yaojianbin33

只需要为blue和yellow各选一个位置就行了，C(5,1)*C(4,1)=20