8.32 PLANNING A SURVEY You are planning a sample survey of small businesses in your area. You will choose an SRS of businesses listed in the telephone book's Yellow Pages. Experience shows that only about half the businesses you contact will respond. 42 142 (a) If you contact 150 businesses, it is reasonable to use the binomial distribution with n = 150 and p = 0.5 for the number X who respond. Explain why. B: Only two choices, respond or not I: It is reasonable to believe that all responses are independent N: n= 150 S: All have the same probability of success (response) = 0.5 %3D (b) What is the expected number (the mean) who will respond? u =150(0.5) = 75 responses 7142 (c) What is the probability that 70 or fewer will respond? (Use the normal approximation.) O = \npq = s0 (0.5)(0.5) = 6.1237 %3D 70-75 P(X s70): P(Zs - P(Zs-0.82) -0.2071 =P(Zs-0.82)=0.2071 %3D 6.1237 (d) How large a sample must you take to increase the mean number of respondents to 100? You must increase the sample to 200, since (200)(0.5) = 100. %3D
Contingency Table
A contingency table can be defined as the visual representation of the relationship between two or more categorical variables that can be evaluated and registered. It is a categorical version of the scatterplot, which is used to investigate the linear relationship between two variables. A contingency table is indeed a type of frequency distribution table that displays two variables at the same time.
Binomial Distribution
Binomial is an algebraic expression of the sum or the difference of two terms. Before knowing about binomial distribution, we must know about the binomial theorem.
See attached and solve c) substituting 142 businesses for the 150 on the original
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