THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION

Essay

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
Of the 1400 colleges in the United States,370 have two-year schools and 1030 have four-year schools.In a random sample of 40 two-year schools,it was found that 10 of the schools do not have any faculty holding a Ph.D.degree.In an independent random sample of 60 four-year schools,it was found that only 6 of the schools do not have any faculty holding a Ph.D.degree.
-The mean amount of the 800 mortgages taken out in the city of Grand Rapids,Michigan,in the past year must be estimated.Based on previous experience,a real estate broker knows that the population standard deviation is likely to be about $25,000.If a 95% confidence interval for the population mean extends $2,400 on each side of the sample mean,how many sample observations are needed if a simple random sample is taken?