SOLUTION: Past experience indicates that 30% of all individuals entering a certain store decide to make a purchase. Using a) the binomial distribution and b) the normal approximation to the

Question 654342: Past experience indicates that 30% of all individuals entering a certain store decide to make a purchase. Using a) the binomial distribution and b) the normal approximation to the binomial, find the probability that 10 or more of the 30 individuals entering the store in a given hour will decide to make a purchase.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Past experience indicates that 30% of all individuals entering a certain store decide to make a purchase. Using a) the binomial distribution and
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a. P(10<= x <=30) = 1 - P(30,0.30,9) = 0.4112
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b) the normal approximation to the binomial, find the probability that 10 or more of the 30 individuals entering the store in a given hour will decide to make a purchase.
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b.mean = np = 0.3*30 = 9
std = sqrt(npq) = sqrt(9*0.7) = 2.510
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P(10<= x <=30) = P(9.5<= x <- 30.5)
z(9.5) = (9.5-9)/2.510 = 0.1992
z(30.5) = (30.5-9)/2.51 = 8.57
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P(0.1992<= z <= 8.57) = 0.4211
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Cheers,
Stan H.
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