A public health unit wants to sample death records for the past year in Toronto to estimate the proportion of the deaths that were due to accidents. They want the estimate to be accurate to within 0.02 with probability 0.95.

(a) Find the necessary sample size if, based on data published by Statistics Canada (www.statcan.gc.ca), they believe that this proportion does not exceed 0.10.

(b) Suppose that in determining n, they use the safe approach that sets π = 0.50 in the appropriate formula.

Then how many records need to be sampled? Compare the result to the answer in part (a), and note the reduction in sample size that occurs by making an educated guess for π.