GWD-30 数学 请教

dominique11

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

uavkai

先從五部車中任選一部出來放在第一個停車位所以有5種可能，接著再從四部車選一部出來放在第二個停車位所以有4種可能...以此類推所以全部有5x4x3x2x1=120總可能

但是又因為有三部車有相同顏色所以要除以3!=6

120/6 ＝20

答案應該是A

[此贴子已经被作者于2008-8-29 23:46:54编辑过]