A researcher found that a 98% confidence interval for the me…

A researcher found that a 98% confidence interval for the mean hours per week spent studying by college students was (13, 17). Which is true?  I. There is a 98% chance that the mean hours per week spent studying by college students is between 13 and 17 hours.II. 98% of college students study between 13 and 17 hours a week.III. Students average between 13 and 17 hours per week studying on 98% of the weeks. 

At one vehicle inspection station, 13 of 52 trucks and 11 of…

At one vehicle inspection station, 13 of 52 trucks and 11 of 88 cars failed the emissions test. Assuming these vehicles were representative of the cars and trucks in that area, what is the standard error of the difference in the percentages of all cars and trucks that are not in compliance with air quality regulations?