1. The weight of boxes of red gravel may be modelled by a normal distribution with mean 25.8kg standard deviation 0.5kg. Determine the probability that a randomly selected box of red gravel will weight:

. Less than 25kg

. Between 25.5 and 26.5 kg

2. The average drive to office is 9.6 miles. Assume standard deviation is 1.8. If random sample of 36 employed who derive to office are selected, find the probability that mean of sample miles driven to office is between 9 and 10 miles.

3. The data for the Car Rental Company is given:

Company | Cars | Revenue

A | 63 | 7

B | 29 | 3.9

C | 20.8 | 2.1

D | 19.1 | 2.8

E | 13.4 | 1.4

F | 8.5 | 1.5

Compute the linear correlation coefficient for the data and find the equation of regression line.

4. A hospital reports that the average cost of rehabilitation for stroke victims is 24672 BD. To see if the average cost of rehabilitation is different at a particular hospital, a researcher selects 35 victims at random and find the average cost is 26343 BD. Standard deviation is 3251 BD. At =0.01, can it be concluded that the average cost of rehabilitation at a particular hospital is different form 24672 BD.