Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 Re: Help Me ! » Permutations and Combinations » 2008-02-06 01:21:01

Thanks again,
I got the first one but the second one is a bit confusing.......but  4c2 = 4!/2!.2! = 6 then the final answer is 6x6p2 + 6x4c2 = 6x30 + 6x6 = 180+36 = 216.

#2 Help Me ! » Arranging people in a circular table » 2008-02-06 01:05:37

goed
Replies: 1

A meeting involves 4companies, each company sends three representatives- MD,CA,CS.In how many ways can the twelve people can be arranged in a circular table if the three people from each company  sit together with MD in between the CS and CA in each case??

This is how I tried....but couldn't get the right answer(96)

Step 1: There are 4 companies sending 3people and all the three people should sit together so there are 4 sets which can be arranged in 4! ways i.e 24 ways
Step 2: MD should alwys be between CS and CA so CS and CS can be arranged in 2! ways i.e 2ways

Hence the total number of ways  is 24x2= 48 ways.

But i know i didn't arrange them in a circular table....how can we do that??

Thanks

#3 Re: Help Me ! » Permutations and Combinations » 2008-02-06 00:31:56

Thank you for your quick reply.....but the answers are 1596(for selecting 4 letters from the given word) and 198 (containing 2 R's)and no clue how he gets that?? Waiting for your reply

#4 Help Me ! » Permutations and Combinations » 2008-02-05 23:05:04

goed
Replies: 5

How to find the total number of permutations of four letters selected from the word 'ARRANGEMENT'.How many of these permutations contain two R's??

Board footer

Powered by FluxBB