Question 26 An increasing number of consumers believe they have to look out for

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Question 26 An increasing number of consumers believe they have to look out for themselves in the marketplace. According to a survey conducted by the Yankelovich Partners for USA WEEKEND magazine, 60% of allconsumers have called an 0 or 90 telephone number for format on about so ne product Supp n ran sample ons o s en esa acted s interviewed about their buying habits. (Round answers to 3 decimal places when calculating using Table A2) a. What is the probability that 11 or more of these consumers have called an 800 or 900 telephone number for information about some product? b. What is the probability that more than 14 of these c. what is the probability that fewer than 7 have called consumers have called an 800 or 900 telephone number for information about some product? of these consumers have called an 800 or 900 telephone number for information about some product Question Attempts: 0 of 1 used SAVE FOR LATER

Explanation / Answer

a) n = 19

    p = 0.6

P(X > 11) = P(X = 11) + P(X = 12) + P(X = 13) + P(X = 14) + P(X = 15) + P(X = 16) + P(X = 17) + P(X = 18) + P(X = 19)

              = 19C11 * (0.6)^11 * (0.4)^8 + 19C12 * (0.6)^12 * (0.4)^7 + 19C13 * (0.6)^13 * (0.4)^6 + 19C14 * (0.6)^14 * (0.4)^5 + 19C15 * (0.6)^15 * (0.4)^4 + 19C16 * (0.6)^16 * (0.4)^3 + 19C17 * (0.6)^17 * (0.4)^2 + 19C18 * (0.6)^18 * (0.4)^1 + 19C19 * (0.6)^19 * (0.4)^0 = 0.668

b) P(X > 14) = P(X = 15) + P(X = 16) + P(X = 17) + P(X = 18) + P(X = 19)

                    = 19C15 * (0.6)^15 * (0.4)^4 + 19C16 * (0.6)^16 * (0.4)^3 + 19C17 * (0.6)^17 * (0.4)^2 + 19C18 * (0.6)^18 * (0.4)^1 + 19C19 * (0.6)^19 * (0.4)^0 = 0.070

c) P(X < 7)

= P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) + P(X = 5) + P(X = 6)

= 19C0 * (0.6)^0 * (0.4)^19 + 19C1 * (0.6)^1 * (0.4)^18 + 19C2 * (0.6)^2 * (0.4)17 + 19C3 * (0.6)^3 * (0.4)^16 + 19C4 * (0.6)^4 * (0.4)^15 + 19C5 * (0.6)^5 * (0.4)^14 + 19C6 * (0.6)^6 * (0.4)^13 = 0.012

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