Q31 of 158 Page 33

A bag contains 5 red, 6 white and 7 black balls. Two balls are drawn at random. What is the probability that both balls are red or both are black?

given: bag which contains 5 red, 6 white, 7 black balls

formula:


two balls are drawn at random


total possible outcomes are 18C2


therefore n(S)= 18C2=153


let E be the event that both balls are either red or black


n(E)=5C2+7C2=31


probability of occurrence of the event is




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