Question

31.Lefties Find the sample size needed to estimate the percentage of California residents who are left-handed. Use a margin of error of three percentage points, and use a confidence level of 99%. a. Assume that pn and qn are unknown. b. Assume that based on prior studies, about 10% of Californians are lefthanded. c. How do the results from parts (a) and (b) change if the entire United States is used instead of California

Answer 1

Answer:

a. 1844

b. 664

Step-by-step explanation:

a. No estimate of proportion is given so we will assume:  

{p} = {q} = 0.5

For 99% confidence, z = 2.576

E = 0.03  

Hence, Required sample size  n = (0.5)*(0.5)*(2.576/0.03)^2  = 1844

b. {p} = 0.10

{q} = 1 - {p}

{q} = 1 - 0.10

{q} = 0.90  

For 99% confidence, z = 2.576

E = 0.03

Hence,  Required sample size  n = (0.1)*(0.9)*(2.576/0.03)^2  = 664

c. There would have been no effect on parts a and b if entire US has been chosen because minimum sample size required is not dependent on population size.