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Misc 1 - A box contains 10 red marbles, 20 blue, 30 green - Using combination

Misc 1 - Chapter 16 Class 11 Probability - Part 2

Misc 1 - Chapter 16 Class 11 Probability - Part 3

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Misc 1 A box contains 10 red marbles, 20 blue marbles and 30 green marbles. 5 marbles are drawn from the box, what is the probability that all will be blue? 5 marbles are to be chosen from 60 (10 red + 20 blue + 30 green) Hence n(S) = 60C5 Let A be the event that all are blue Hence out of 20 blue marbles 5 will be chosen n(A) = 20C5 P(A) = ( ) ( ) = Misc 1 A box contains 10 red marbles, 20 blue marbles and 30 green marbles. 5 marbles are drawn from the box, what is the probability that (ii) at least one will be green? P(atleast one will be green) = 1 P(none of marbles are green) Lets first calculate probably that none of marbles are green Let B be the event that none of marbles are green If marble is not green, it will be red or blue Hence, out of (20 + 10 = )30 marbles, 5 are to be selected Hence n(B) = 30C5 P(B) = ( ) ( ) = 30 5 60 5 Hence, P(atleast one will be green) = 1 P(none of marbles are green) = 1

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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 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.