King Fahd University of Petroleum & Minerals

Mathematical Sciences

Stat319-Term033

                                                          Quiz #5                                Sections: 3 & 4

Name:                                                        ID                                           Serial:

A materials researcher wishes to use the following sample curing-time data to compare two methods for applying an adhesive;

Method A

14

16

13

15

16

13

14

14

15

11

Method B

8

9

12

6

7

7

10

5

14

10

Given that;

1. What is the least sample size needed for constructing a CI for the mean of method A, with a precision of 0.95 and a reliability of 0.98?

Solution:

 

2. Construct a 98% CI for the difference between the two method means. Assume normal populations with equal variances.

Solution:

A 98% C.I for   is:

 

3. Construct a 98% CI for the standard deviation of method B. State necessary assumptions.

Solution:

A 98% C.I. for  is:

Assumptions: The population is normally distributed