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Show ALL of your work. Box or circle your answers. Round calculations to at leas

ID: 3070718 • Letter: S

Question

Show ALL of your work. Box or circle your answers. Round calculations to at least TWO decimal places. Do NOT round probabilities found in tables. Good luck! (10) According to a recent poll, 30% of Americans prefer Pepsi over Coca-Cola. Let X = the number of people that prefer Pepsi out of a random sample of 10 a) Using the pmf, find the probability that EXACTLY 5 people prefer Pepsi. (5 pts) 1. Americans b) Using the probability tables, find the probability that AT LEAST 7 people prefer Pepsi. (5 pts) S1

Explanation / Answer

a)

P(x) = 0.3

P(X =5) = 10C5 *(0.3^5)*(0.7^5) = 0.10

b)

P(X>=7) = P(X=7)+P(X=8)+P(X=9)+P(X=10) = 0.011