Straight Forward Probablility Question

pocketjacks · #1 06-05-2006, 01:12 PM

There are 20 students in your gym class. Your teacher divides the class into two equal softball teams. Your team draws names one by one to determine the batting order. What is the probability that 1 of the 7 freshman on the team will be chosen first, in any order?

Related to the top question.

find the probability that 3 of the 7 freshmen will be chosen last, in any order.

Any help and explanation would be very much appreciated.

Thanks in advance!

toms2866 · #2 06-10-2006, 01:57 AM

Here are the answers for your homework assignment...

Question 1: 10 players, 7 are freshman. Chance a freshman picked first = 7/10.

Question 2: Same chance as 3 freshman picked first = 7/10 * 6/9 * 5/8.

toms2866 · #3 06-10-2006, 02:03 AM

If you meant 7 freshman in the 20 students...

Question 1: 10 players, 3.5 are freshman. Chance a freshman picked first = 3.5/10.

Question 2: 3.5/10 * 2.5/9 * 1.5/8

AaronBrown · #4 06-10-2006, 02:17 PM

I agree with the first two answers, which assume 7 out of the 10 students on the team are freshmen. If we assume 7 out of 20, the answer to question 1 is correct, but question 2 is not.

The division into two teams is just a distraction if we are given the number of freshmen in the 20 person gym class. The chance than the last three players drawn for one specific team are freshmen is 7/20 * 6/19 * 5/18.

toms2866 · #5 06-13-2006, 07:53 PM

[ QUOTE ]
the answer to question 1 is correct, but question 2 is not.

[/ QUOTE ]
You're right.