Assume that a sample is used to estimate a population proportion p. Find the margin of error M.E. that corresponds to a sample of size 221 with 27.1% successes at a confidence level of 99.9%.

M.E. = %

Report answer accurate to one decimal place (as a number of percentage points).  Answer should be obtained without any preliminary rounding (however, the critical value may be rounded to 3 decimal places).