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Misc 10 - From a class of 25 students, 10 are chosen for excursion

Misc 10 - Chapter 7 Class 11 Permutations and Combinations - Part 2

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Misc 10 From a class of 25 students, 10 are to be chosen for an excursion party. There are 3 students who decide that either all of them will join or none of them will join. In how many ways can the excursion party be chosen? There are 2 options All 3 join Remaining 7 to be chosen from 25 – 3 = 22 students Number of ways = 22C7 = 22!/7!(22 − 7)! = 22!/7!(15)! = 170544 All 3 don’t join Remaining 10 chosen from 22 students Number of ways = 22C10 = 22!/10!(22 − 10)! = 22!/10!12! = 646646 Thus, Total number of ways = 170544 + 646646 = 817190

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.