Each signal that a certain ship can make is comprised of 3 different flags hanging vertically in a particular order. How many unique signals can be made by using 4 different flags?
A. 10
B. 12
C. 20
D. 24
E. 36
此题,从4面旗子里面选3面排列就好啦~
P43=4*3*2=24...还真不是一般的简单~LZ是题目没看懂吗??
此题,从4面旗子里面选3面排列就好啦~
P43=4*3*2=24...还真不是一般的简单~LZ是题目没看懂吗??
3 different flags hanging vertically in a particular order
这句话很容易让人产生3 different flags 是怎么vertically in a particular order的想法,把问题项复杂,导致错误思路!:)
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