SOLUTION: Use the normal distribution to approximate the desired probability. A coin is tossed 20 times. A person, who claims to have extrasensory perception, is asked to predict the outcome

Question 1064881: Use the normal distribution to approximate the desired probability. A coin is tossed 20 times. A person, who claims to have extrasensory perception, is asked to predict the outcome of each flip in advance. She predicts correctly on 13 tosses. What is the probability of being correct 13 or more times by guessing?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
np=10 mean
np(1-p)=variance=5
sd=sqrt (5) or 2.236
probability of 13 or more is (13-10)/2.236=probability z >1.342, which is 0.0898
The probability is 20C13 (0.5^13)(0.5^7)=0.0739, which is the exact probability.
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