Example 15 - Chapter 7 Class 11 Permutations and Combinations (Term 2)
Last updated at Dec. 8, 2016 by Teachoo
Examples
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Example 3 Important
Example 4 Important
Example 5
Example 6 (i)
Example 6 (ii)
Example 7
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Example 10
Example 11 Important
Example 12 (i) Important
Example 12 (ii)
Example 13
Example 14 Important
Example 15 You are here
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Example 20 Important
Example 21 Important
Example 22 Important
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Example 24 Important
Chapter 7 Class 11 Permutations and Combinations (Term 2)
Serial order wise
- Ex 7.1
- Ex 7.2
- Ex 7.3
- Ex 7.4
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Examples
- Miscellaneous
Transcript
Example 15 In how many ways can 4 red, 3 yellow and 2 green discs be arranged in a row if the discs of the same colour are indistinguishable ? Total number of discs = 4 red + 3yellow + 2 green n = 9. Since color are repeating so we use this formula π!/π1!π2!π3! Here n = 9 Out of 9 discs, 4 red, 3 yellow and 2 green & p1 = 4, p2 = 3, p3 = 2 The number of arrangement = π!/π1!π2!π3! = 9!/(4! 3! 2!) = (9 Γ 8 Γ 7 Γ 6 Γ 5 Γ 4!)/(4! Γ (3 Γ 2 Γ 1)(2 Γ 1)) = (9 Γ 8 Γ 7 Γ 6 Γ 5)/(3 Γ 2 Γ 2) = 1260. Hence, total number of arrangements is 1260
