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  1. Chapter 7 Class 11 Permutations and Combinations
  2. Serial order wise

Transcript

Ex 7.4, 4 In how many ways can a team of 3 boys and 3 girls be selected from 5 boys and 4 girls? Selecting 3 Boys We have to select 3 boys from 5 boys Here, n = 5 & r = 3 Number of ways = nCr = 5C3 = 5!/3!(5 −3)! = 5!/3!2! = 10 Selecting 3 girls Similarly we have to select 3 girls from 4 girls Here n = 4 & r = 3 Number of ways = nCr = 4C3 = 4!/(3!(4 −3)!) = (4 × 3!)/(3! × 1!) = 4 Hence, Total number of ways = 10 × 4 = 40 Hence, 40 ways to selecting 3 boys & 3 girls from 5 boys & 4 girls

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.