1. When calculating sample size, how can a researcher decide on the level of accuracy to use? What about level of confidence? What about variability with a percentage?

2. Using the formula provided in your text, determine the approximate sample sizes for each of the following cases, all with precision (allowable error) of ±5%:
a. Variability of 30%, confidence level of 95%.
b. Variability of 60%, confidence level of 99%.
c. Unknown variability, confidence level of 95%.