Question 1070368: On a five-question multiple choice test, each question has four choices (a,b,c,d), only one of which is correct. if you guess randomly, find the probability that you pass the test; that is, find the probability of getting 4 or more correct. Remember not to add rounded numbers. Don't round until your final answer. *Find the probability of exactly 4 correct OR exactly 5 correct)
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! Use the binomial probability function, that is
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Probability(P) ( k successes out of n trials) = nCk * p^k * (1-p)^(n-k), where nCk is combinations of n things taken k at a time, p is probability of a suceess
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for this problem p = 1/4 = 0.25
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P ( k > or = 4 ) = P ( k = 4 ) + P ( k = 5 )
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P ( k > or = 4 ) = 0.0146484375 + 0.0009765625 = 0.015625 is approximately 0.02
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P ( k = 4 or k = 5) = P ( k = 4) + P ( k = 5 )
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