Last updated at May 29, 2018 by Teachoo

Transcript

Misc 5 Out of 100 students, two sections of 40 and 60 are formed. If you and your friend are among the 100 students, what is the probability that • you both enter the same sections? n(S) = 100C40, n(A) = 98C38 P(A) = 𝑛(𝐴)𝑛(𝑆) = 𝟗𝟖𝑪𝟑𝟖𝟏𝟎𝟎𝑪𝟒𝟎 = 98C38 ÷ 100C40 = 98!38! 98 −38! × 100!40! 100 − 40! = 98!38!60! ÷ 100!40!60! = 98!38!60! × 40!60!100! = 98! × 40! × 60!38! × 60! × 100! = 40 × 39100 × 99 Probability that two students enter same section = Probability that both enter Section A + Probability that both enter Section B = P(A) + P(B) = 40 × 39100 × 99 + 60 × 59100 × 99 = 15609900 + 35409900 = 156990 + 354990 = 156 + 354990 = 510990 = 5199 = 𝟏𝟕𝟑𝟑 Misc 5 Out of 100 students, two sections of 40 and 60 are formed. If you and your friend are among the 100 students, what is the probability that (b) you both enter the different sections? Probability that they enter different section = 1 – Probability that both enter in same section = 1 – 1733 = 33 − 1733 = 𝟏𝟔𝟑𝟑

About the Author

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.