210k views
2 votes
A jury of 12 people is chosen from 20 men and 30 women. What is the probability that

a) there is an equal number of men and women on the jury?

b) there are at least two men on the jury?

User Duncan C
by
7.6k points

2 Answers

2 votes

Final answer:

The probabilities for a jury to have an equal number of men and women and to have at least two men are calculated using combinations. For an equal split, it's (C(20,6) * C(30,6)) / C(50,12), and for at least two men, it's 1 - ((C(30,12) + C(20,1)*C(30,11)) / C(50,12)).

Step-by-step explanation:

Probability of Jury Composition

To answer these questions, we'll use combination formulas since we are dealing with selecting a group without regard to order, from a larger pool.

a) Equal number of men and women on the jury:

The total number of possible juries is the combination of 50 people taken 12 at a time: C(50,12).

For an equal number of men and women, we need 6 men and 6 women. The number of ways to choose 6 men out of 20 is C(20,6), and the number of ways to choose 6 women out of 30 is C(30,6). So, the probability is the product of these combinations divided by the total number of possible juries: (C(20,6) * C(30,6)) / C(50,12).

b) At least two men on the jury:

The probability of having at least two men is 1 minus the probability of having 0 or 1 man. The number of ways to have 0 men and all women is C(30,12), and 1 man and 11 women is C(20,1)*C(30,11). So, the probability is 1 - ((C(30,12) + C(20,1)*C(30,11)) / C(50,12)).

User Gabriel Ben Compte
by
8.2k points
2 votes

Answer:

6 men 6 women or 2 men 10 women

User Comfort Eagle
by
8.5k points