Multiple Choice Test: Binomial ProbabilityDate: 08/05/97 at 18:55:12 From: Heather Subject: Multiple choice test A multiple choice test consists of 9 questions with 5 choices for each answer. If a student guesses randomly, find the probability of each of the following events: 1. The student gets 5 correct 2. The student gets at least 5 correct 3. The student gets 2 correct answers 4. The student gets fewer than 3 correct answers. Date: 08/06/97 at 11:55:26 From: Doctor Anthony Subject: Re: Multiple choice test This is binomial probability with n = 9, p = 1/5, q = 4/5 1. P(5) = 9C5 (1/5)^5 (4/5)^4 = 0.016515 2. At least 5 is = P(5) + P(6) + P(7) + P(8) + P(9) P(6) = 9C6 (1/5)^6 (4/5)^3 = .0027525 and so on..... 3. P(2) = 9C2 (1/5)^2 (4/5)^7 = 0.301989 4. P(< 2) = P(0) + P(1) P(0) = (4/5)^9 = 0.1342177 P(1) = 9C1 (1/5) (4/5)^8 = 0.301989 So P(<2) = Sum of these = 0.43621 -Doctor Anthony, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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