In a parent-teacher association, there are 5 couples. A project team of 4 people is going to be selected from the 5 couples. Find the number if ways to form the team if
(a) the team consists of no couple;
(b) the team consists of exactly one couple.
Can someone help to solve this question??
Maths: Combination
2011-12-11 10:47 am
回答 (1)
2011-12-11 8:15 pm
✔ 最佳答案
(a) First select 4 couples from among 5, there are C(5,4)=5 waysThen there are 2 choices for each couple, total number of ways=5×2^4=80 (b) Select the couple first, there are C(5,1)=5 waysThen select 2 more couples C(4,2)=6 waysSelect 1 person from each of these 2 couples there are 2^2=4 waysTherefore total number of ways=5×6×4=120 ways
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