
Binomial Distribution
Binomial Distribution
Last updated at Dec. 16, 2024 by Teachoo
Transcript
Question 9 On a multiple choice examination with three possible answers for each of the five questions, what is the probability that a candidate would get four or more correct answers just by guessing ? Let X : be the number of correct answers by guessing Guessing an answer is a Bernoulli trial So, X has binomial distribution P(X = x) = nCx 𝒒𝒏−𝒙 𝒑𝒙 n = number of questions = 5 p = Probability of getting correct answer = 13 q = 1 – p = 1 – 13= 23 ∴ P(X = x) = 5Cx 𝟏𝟑𝒙 𝟐𝟑𝟓−𝒙 Probability that he would get four or more correct answers = P(X ≥ 4) = P(4) + P(5) = 5𝐶4 134 231+ 5𝐶5 135 230 = 5 !4 ! 2 35 + 1 35 = 5 × 2 + 1 35 = 10 + 1 35 = 11 35 = 𝟏𝟏𝟐𝟒𝟑