Ex 13.5, 6 - Chapter 13 Class 12 Probability

Transcript

Ex 13.5, 6 A bag consists of 10 balls each marked with one of the digits 0 to 9. If four balls are drawn successively with replacement from the bag, what is the probability that none is marked with the digit 0? Let X : be the number marked on bulb drawn Picking balls is a Bernoulli trial So, X has binomial distribution P(X = x) = nCx n = number of times we pick the bulb = 4 p = Probability of getting digit 0 = 1 10 q = 1 p = 1 1 10 = 9 10 Hence, P(X = x) = 4Cx We need to find Probability that none is marked with 0 i.e. P(X = 0) P(X = 0) = 4C0 1 10 0 9 10 4 0 = 4 ! 4 0 ! 0 ! 1 9 10 4 = 4 ! 4 ! 9 4 10 4 = 9 4 10 4 =