Question

Wework math20spring19mcnelis / hw4_ binomial random vaniables /4 HW4 Binomial Random Variables: Problem 4 Previous Problem Problem List Next Problem (1 point) A quiz consists of 10 mutiple-choice questions, each with 5 possible answers. For someone who makes random guesses for all of the answers, find the probability of passing if the minimum passing grade is 70 % P(pass)-

Answer 1

Solution:- Given that n = 10, p = 0.2

X = 10*0.7 = 7

P(X >= 7) = P(7) + P(8) + P(9) + P(10) = 0.0008 + 0.0001 + 0.0000 + 0.0000 = 0.0009

P(7) = 10C7*0.2^7*0.8^3 = 0.0008

P(8) = 10C8*0.2^8*0.8^2 = 0.0001

P(9) = 10C9*0.2^9*0.8^1 = 0.0000

P(10) = 10C10*0.2^10*0.8^0 = 0.0000

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=> P(X >= 7) = 0.00086