SOLUTION: Use the Normal Approximation to the Binomial Distribution to compute the probability of passing a true/false test of 30 questions if the minimum passing grade is 60% and all respon

Question 1176919: Use the Normal Approximation to the Binomial Distribution to compute the probability of passing a true/false test of 30 questions if the minimum passing grade is 60% and all responses are random guesses.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
n=30 p=0.5
mean is np=15
variance is np(1-p)=7.5
sd is sqrt (V)=2.74
need to get 18 or more right
z > (17..5-15)/2.74 or > 2.5/2.74 or 0.91
that probability is 0.1814, using the normal approximation
the exact value is 0.1808

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