Context

The National Vital Statistics Reports for November 2011 states that U.S. preterm birth rate for 2010 was about 12%. Preterm birth means premature birth. Suppose that this year a random sample of 500 births has 52 that are preterm.

Prompt

Using the estimate from the NVS Report for 2011 and the result from this year's random sample, estimate the percent of preterm births this year with 95% confidence interval. (Be sure to check that a normal model is appropriate and show your work for calculating the 95% confidence in a fashion similar to the examples.)