Posted by **Ashley** on Saturday, December 5, 2009 at 7:01pm.

How many ways can an IRS auditor select 3 of 11 tax returns for an audit?

There are 8 members on a board of directors. If they must form a subcommittee of 3 members, how many different subcommittees are possible?

License plates are made using 3 letters followed by 3 digits. How many plates can be made if repetition of letters and digits is allowed.

At the first tri-city meeting, there are 8 people from town A, 7 people from town B, and 5 people from town C. If a council consisting of 5 people is randoml selected, find the probabilit that 3 are from town A and 2 are from town B.

- Math - Please Help Me! -
**MathMate**, Sunday, December 6, 2009 at 9:30am
The auditor chooses the first return out of 11, that makes 11 choices. For the second, she is left with 10, so there are 11*10 ways. For the third, she has 9 returns left from which to choose, so there are 11*10*9=990 ways to choosing the first 3 returns.

However, out of the 990 ways to choose the returns, each combination (say A,B,C) would have been repeated in 6 different orders, like ABC, BAC, CAB, BCA, ACB, CBA. The number of repetitions can be calculated by 6=3!, where three is the number of returns chosen.

Thus the number of ways she can choose 3 returns would be

11*10*9/3!=990/6=165.

It's your turn to choose the sub-committees and try the rest of the exercises.

If you have difficulties, post what you have or what the difficulties are.

- Math - Please Help Me! -
**bluestar**, Wednesday, December 16, 2009 at 5:50pm
i need help me on math

like 2+2=

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