2007-02-19 22:54:14 · 4 answers · asked by ce6j19912 1 in Science & Mathematics ➔ Mathematics
The probability is the number of combinations of 4 teachers and 3 pupils divided by the number of combinations of 7 people out of 12.
Let's define f(n ,k) to be n!/[k! * (n -k)!]
Then p, our probability is f(7, 4) * f(5, 3) / f(12, 7) = 35 * 10 / 792.
2007-02-19 23:08:40 · answer #1 · answered by Amit Y 5 · 0⤊ 0⤋
Probability of selecting 4 teachers out of 7 is 7! / (7-4)!
Probability of selecting remaining 3 pupils is 5! / (5-3)!
Probability of 4 teachers in the group:
(7! / 3! x 5! / 2!) / (12! / 5!)
= 1/396
2007-02-19 23:39:00 · answer #2 · answered by death approaching 1 · 0⤊ 0⤋
probability is4/12 = 1/3
2007-02-19 23:17:45 · answer #3 · answered by hamd 2 · 0⤊ 0⤋
I think the asnwer is 33.33%
2007-02-19 23:02:20 · answer #4 · answered by Anonymous · 0⤊ 0⤋