Probability question?
2020-11-08 6:05 pm
Hi! I need help on this question. My answer is 12/55 but I need someone to confirm this. Thanks in advance! :)
回答 (2)
2020-11-08 6:24 pm
✔ 最佳答案
Total number of pens= 4 + 6 + 2
= 12
No. of combinations of choosing 3 pens
= ₁₂C₃
= 12!/(9!3!)
= 220
No. of combinations of choosing 1 red pen, 1 green pen and 1 blue pen
= ₄C₁ × ₆C₁ × ₂C₁
= 4 × 6 × 2
= 48
P(1 red pen, 1 green pen and 1 blue pen)
= 48/220
= 12/55
Your answer is correct.
2020-11-08 6:18 pm
Let's consider the situation where we pick a red, green and blue pen in that order.
so, 4/12 x 6/11 x 2/10 => 2/55
Now, the combination of the three colours can be permutated in 3! ways => 6 ways
Hence, 6 x (2/55) => 12/55
:)>
so, 4/12 x 6/11 x 2/10 => 2/55
Now, the combination of the three colours can be permutated in 3! ways => 6 ways
Hence, 6 x (2/55) => 12/55
:)>
收錄日期: 2021-04-25 13:43:04
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20201108100536AAmA4TY