1) The Highway Safety Department wants to study the driving habits of individuals. A sample of 121 cars traveling on the highway revealed an average speed of 60 miles per hour with a standard...

1) The Highway Safety Department wants to study the driving habits of individuals. A sample of 121 cars traveling on the highway revealed an average speed of 60 miles per hour with a standard deviation of 11 miles per hour. Determine Lower Limit (LL) of 98.92% confidence interval estimate for the speed of all cars.

(Please use 2 decimal places for the answer)

2) The monthly starting salaries of students who receive an MBA degree have a population standard deviation of $125. What size sample should be selected to obtain a 0.95 probability of estimating the mean monthly income within $15 or less?

3)

Below you are given ages that were obtained by taking a random sample of 9 undergraduate students. Assume the population has a normal distribution.

What is the Lower Limit of 98% confidence interval for the average age of undergraduate students.

(Please, use 1 decimal place for the answer)