149k views
1 vote
A city council consists of 10 members. Four are Republicans, three are Democrats, and three are Independents. If a committee of three is to be selected, find the probability of selection..

1. All Republicans. Round your answer to five decimal places. ??
2. All Democrats. Round your answer to five decimal places. ??
3. One of each party. Round your answer to five decimal places. ??
4. Two Democrats and one Independent. Round your answer to five decimal places. ??
5. One Independent and two Republicans. Round your answer to five decimal places.??

User Shidhin Cr
by
3.8k points

1 Answer

2 votes
To find the probability of selecting a committee with a certain combination of party members, we can use the formula for combinations:

P(A) = n! / (r! * (n-r)!)

Where:

-P(A) is the probability of event A occurring
-n is the total number of items (in this case, the total number of council members)
-r is the number of items we are choosing (in this case, the number of members on the committee)

Using this formula, we can find the probability of each event as follows:

-All Republicans: There are 4 Republicans on the council, and we are selecting 3 of them for the committee. Therefore, the probability is:
P(A) = 10! / (3! * 7!) = 120 / (6 * 5040) = 1/42 = 0.02381
-All Democrats: There are 3 Democrats on the council, and we are selecting 3 of them for the committee. Therefore, the probability is:
P(A) = 10! / (3! * 7!) = 120 / (6 * 5040) = 1/42 = 0.02381
-One of each party: There are 4 Republicans, 3 Democrats, and 3 Independents on the council, and we are selecting 1 of each for the committee. There are a total of 10 * 9 * 8 = 720 ways to select 1 member from each party. Therefore, the probability is:
P(A) = 720 / (10 * 9 * 8) = 1/56 = 0.017857
-Two Democrats and one Independent: There are 3 Democrats and 3 Independents on the council, and we are selecting 2 Democrats and 1 Independent for the committee. There are a total of 3 * 2 * 3 = 18 ways to select these members. Therefore, the probability is:
P(A) = 18 / (10 * 9 * 8) = 1/280 = 0.003571
-One Independent and two Republicans: There are 4 Republicans and 3 Independents on the council, and we are selecting 2 Republicans and 1 Independent for the committee. There are a total of 4 * 3 * 3 = 36 ways to select these members. Therefore, the probability is:
P(A) = 36 / (10 * 9 * 8) = 1/140 = 0.007143
Thus, the probabilities of selecting a committee with the specified combinations of party members are:

1-All Republicans: 0.02381
2-All Democrats: 0.02381
3-One of each party: 0.017857
4-Two Democrats and one Independent: 0.003571
5-One Independent and two Republicans: 0.007143
User Jeremy Likness
by
3.4k points