Pure math, Amath問題
2009-12-04 6:20 am
Suppose 6 letters are drawn from 'ARRANGE'. How many possible arrangements can be made?
回答 (1)
2009-12-04 8:04 am
✔ 最佳答案
case 1 : Have not draw A : (then double R)total : 6! / 2! = 360 arrangements
case 2 : Have not draw R : (then double A)
total : 6! / 2! = 360 arrangements
case 3 : Have not draw N or G or E : (then double A and double R)
total : 3 * [6! / (2!)(2!) ] = 540 arrangements
All cases TOTAL 360+360+540 =1260 arrangements.
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