1. Chapter 8

2. Problem 8-6

3. Problem 8-15 µ=60 σ=12 2496 48 72

4. Problem 8-15(contd.).2734 63.2266

5. Problem 8-15(contd.) 56 0.1 4 6056      x x x z   4 60   x x  

6. Problems 8-16 Since n=40,the sampling distribution of means will approximate a normal distribution 74 76 77.3962.4943

7. Problem 8-16(Contd.)

8. Problem 8-17 1950

9. Problem 8-18.2852 320 minutes649.12 40 80.  n a x 79. 40 80 330320 7852.5000.2852.)320(.       x z xpb x x 

10. Problem 8-18(Contd.). 4429. 2852 320 350 58.1 40 80 330350 7281.4429.2852.)350320(.       x z xpc x 

11. Problem 8-18 contd..

12. =110,000 = 40,000/ 50 a. = / n = 40,000/ 50 = 5657 b. Normal distribution Problem 8-34

13. c..1368.3632 112,000 X =110,000.35 Z P(X> 112,000)=.5000 -.1368=.3632 Problem 8-34 cont’d

14. d..4616 100,000 -1.77 Problem 8-34 cont’d P( X> 100,000)=.4616 +.5000=.9616 Z

15. e..1368.4616 100,000 112,000 X -1.77.35 Problem 8-34 cont’d P(100,000<X< 112,000)=.4616 +.1368 =.5984 Z

16. Problem 8-35.3238.93Z 8238.3238.5000.)1.25( 93. 60 5.2 8.241.25       xp n x z x 