Many states are carefully considering steps that I would hel

Many states are carefully considering steps that I would help them collect sales taxes on items purchased through the Internet. How many randomly selected sales transactions must be surveyed to determine the percentage that transpired over the Internet? Assume that we want to be 90% confident that the sample percentage is within eight percentage points of the true population percentage for all sales transactions.

Solution

n = (z*/ME)^2 pq ME = 0.05, z* = 1.645 for 90% confidence and we use p=q=0.5 with no prior info n = (1.645/.05)^2 (0.5)(0.5) = 165