The probability that a person has an unlisted phone number is0.15. The district
ID: 2917907 • Letter: T
Question
The probability that a person has an unlisted phone number is0.15. The district manager of a political action group isphoning people urging them to vote. In a district with 416households all households have phones. What is the probabilitythat: 1.) 50 or fewer households in the district will have unlistednumbers? 2.)345 or more will have listed phone numbers? 3.) between 40 and 80 will have unlisted phone numbers? The probability that a person has an unlisted phone number is0.15. The district manager of a political action group isphoning people urging them to vote. In a district with 416households all households have phones. What is the probabilitythat: 1.) 50 or fewer households in the district will have unlistednumbers? 2.)345 or more will have listed phone numbers? 3.) between 40 and 80 will have unlisted phone numbers?Explanation / Answer
E= NP=4 16 x .15 = 62.4
Var = np (1-p) = 53
SD=sqrt Var = 7.3
50 is 62.4-50 / 7.3 = 1.69 Z score or 4.5%
That is how you solve this type of problem
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