In: Statistics and Probability
2. As a newly hired manager of a company thatprovides cell phone service, you want to determine the percentage of adults in your state who live in a household with cell phones and no land-line phones. How many adults must you survey? Assume that you want to be 90% confident that the sample percentage is within threepercentage points of the true population percentage
if possible include graph
Solution :
Given that,
= 0.5
1 - = 1 - 0.5 = 0.5
margin of error = E = 3% = 0.03
At 90% confidence level
= 1 - 90%
= 1 - 0.90 =0.10
/2
= 0.05
Z/2
= Z0.05 = 1.645 ( Using z table )
Sample size = n = (Z/2 / E)2 * * (1 - )
= (1.645 / 0.03)2 * 0.5 * 0.5
=751.6736
=752