Author Topic: permutation and combination question  (Read 1232 times)

Offline ashwinkandel

  • SF Citizen
  • ***
  • Posts: 144
  • Reputation: 521
permutation and combination question
« on: January 14, 2011, 11:58:57 am »
) Different colored pegs, each of which is painted in one and only six of the colors, white red blue Black green yellow are to be placed in four holes.

O O O O

With one peg in each hole. the pegs of the same color are identical.Calculate how many different arrangements of pegs placed in the four holes so that they are all occupied can be made from:
12 pegs, two of each colors.

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: permutation and combination question
« Reply #1 on: January 19, 2011, 10:12:14 pm »
Choose 2 colours from 6 in 6C2=15 ways.
Say colour 1 and colour 2
1122
1212
1221
2211
2121
2112
 ie 6*15=90 ways