17.7 Of the 1,395 colleges in the United States, 364 have 2-year schools. In a random sample of 40 two-year schools, it was found that the text Statistics Can Be Fun was used in 10 of the schools. In an independent random sample of 60 four-year schools, this text was used by 8 of the sample members.

a. Find an estimate of the proportion of all colleges using this text, using an unbiased estimation procedure.

b. Find a 95% confidence interval for the proportion of all colleges using this text.