Last updated at Dec. 8, 2016 by Teachoo

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 ๐!/๐1!๐2!๐3! Here n = 9 Out of 9 discs, 4 red, 3 yellow and 2 green & p1 = 4, p2 = 3, p3 = 2 The number of arrangement = ๐!/๐1!๐2!๐3! = 9!/(4! 3! 2!) = (9 ร 8 ร 7 ร 6 ร 5 ร 4!)/(4! ร (3 ร 2 ร 1)(2 ร 1)) = (9 ร 8 ร 7 ร 6 ร 5)/(3 ร 2 ร 2) = 1260. Hence, total number of arrangements is 1260

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Chapter 7 Class 11 Permutations and Combinations

Serial order wise

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.