Suppose you want have a coin that you think might not be exactly
fair, that is the probability of a head might be slightly different
from 0.5. You would like to produce a 95% confidence interval for
p, the true probability of a head. You decide that you would like
the margin of error for your interval to be plus or minus 0.001
(that is plus or minus 0.1%).
How many times, n, do you need to toss the coin...