Permutation and Combination
There are 4 scouts and 5 girl guides.Find the number of arragements if (a)the scouts stand to each other(b)no scouts stand to each other
A coach wants to divide 12 athlets into 3 groups of 3 ,4 5.Find the number of ways of forming a group.
- 自由自在Lv 79 年前最愛解答
(1) (a) If all boy scouts stand next to each other, consider them as a group to be arranged with the 5 girl guidesThere are (1+5)!=720 waysIncluding the arrangement among the scouts, there are 720×4!=17280 ways(b) If no scout stands next to each other, then the persons can be arranged asSGSGSGSGG, GSGSGSGSG, or GGSGSGSGS total 3 waysConsider the relative arrangements of the scouts and guides, there are3×4!×5!=8640 ways