It is reported that 24 of American households use a cell pho

It is reported that 24% of American households use a cell phone exclusively for their telephone service. In a sample of eleven 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 7 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

Solution

It is reported that 24% of American households use a cell phone exclusively for their telephone service. In a sample of eleven households, find the probability that:

n=11

p=0.24

Binomial distribution used

P(X=x) = (_nC_x) p^x (1-p)^n-x   

P(X=0) = (₁₁C₀) 0.24⁰ (1-0.24)^11-0

=0.0489  

Probability =0.0489

P( x=7) =0.0050

Probability=0.0050

Mean

Expectation = np = 11*0.24

=2.6400