It is reported that 18% of American households use a cell phone exclusively for

Question

It is reported that 18% of American households use a cell phone exclusively for their telephone service. In a sample of ten households, find the probability that:    a. No household uses a cell phone as their exclusive telephone service. (Round your answer to 4 decimal places.)      Probability b. Exactly 5 households exclusively use a cell phone for telephone service. (Round your answer to 4 decimal places.)      Probability c. Find the mean number of households exclusively using cell phones. (Round your answer to 4 decimal places.)      Mean

Explanation / Answer

Let X be the number of households out of 10 who use their cell phone exclusively for their telephone service.

X follow binomial distribution with parameters, p = 0.18 and n = 10.

a. P(No household uses a cell phone as their exclusive telephone service)

= Binomial (x=0, n=10) = 10C0*(0.18^0)*(1-0.18)^10 = 0.1374

b. P(Exactly 5 households exclusively use a cell phone for telephone service) = Binomial(x=5,n=10)

= Binomial (x=5, n=10) = 10C5*(0.18^5)*(1-0.18)^5 = 0.0176

c. the mean number of households exclusively using cell phones = n*p = 10*0.18 = 1.8

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