A principal at a large high school wants to estimate the number of days freshmen regularly ride the bus to school. The principal randomly selects 35 freshmen and asks them how many days per week they ride the school bus. The
principal constructs a 90% confidence interval for the true mean number of days freshmen ride the bus to school per
week. Which of the following would decrease the margin of error?
O using a sample of size 30
O using a sample of size 40
O constructing a 95% confidence interval
O constructing a 99% confidence interval