Question

1)Find the critical value z_α/2 needed to construct a(n) 97% confidence interval

2)A college admissions officer takes a simple random sample of 110 entering freshmen and computes their mean mathematics SAT score to be 465. Assume the population standard deviation is

Construct a 90% confidence interval for the mean mathematics SAT score for the entering freshmen class.

3)

In a small-overlap front crash test, a car is crashed into a simulated telephone pole and the maximum intrusion of debris into the passenger compartment of a specific model of car is measured. This intrusion is normally distributed with a standard deviation of 2.5 cm.

How many cars must be crashed to establish that a 98% confidence interval for the mean intrusion of debris into the passenger compartment will have a margin of error of 0.3 cm?

Answer 1