A group of 5 students is to be selected randomly from 10 boys and 5 girls. Find the probability that the group will consist of
a) 5 boys
b) 3 boys and 2 girls
c) at least 3 boys
d) at most 3 boys
F.6 maths(4)
2010-03-30 7:30 am
回答 (1)
2010-03-30 7:46 am
✔ 最佳答案
Total possible no. of combinations = 15C5 = 3003a) No. of possible combinations = 10C5 = 252
So prob = 252/3003 = 12/143
b) No. of possible combinations = 10C3 x 5C2 = 1200
So prob = 1200/3003 = 400/1001
c) For 4 boys and 1 girl, no. of poss. combinations = 10C4 x 5C1 = 1050
So required prob = 12/143 + 400/1001 + 1050/3003 = 834/1001
d) P(At most 3 boys) = 1 - P(At least 3 boys) + P(3 boys)
= 1 - 834/1001 + 400/1001 = 81/143
參考: Myself
收錄日期: 2021-04-24 23:19:31
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