Solutions Manual for Statistics for Engineers and Scientists 6th Edition By William Navidi

Solutions Manual for
to accompany
STATISTICS FOR ENGINEERS AND SCIENTISTS, 6th ed.
Prepared by
William Navidi SECTION 1.1 1
Chapter 1
Section 1.1
1. (a) The population consists of all the times the process could be run. It is conceptual.
(b) The population consist of all the registered voters in the state. It is tangible.
(c) The population consist of all people with high cholesterol levels. It is tangible.
(d) The population consist of all concrete specimens that could be made from the new formulation. It is conceptual.
(e) The population consist of all bolts manufactured that day. It is tangible.
(iii). It is very unlikely that students whose names happe 2. n to fall at the top of a page in the phone book will differ
systematically in height from the population of students as a whole. It is somewhat more likely that engineering
majors will differ, and very likely that students involved with basketball intramurals will differ.
3. (a) False
(b) True
4. (a) False
(b) True
5. (a) No. What is important is the population proportion of defectives; the sample proportion is only an approxima-
tion. The population proportion for the new process may in fact be greater or less than that of the old process.
(b) No. The population proportion for the new process may be 0.12 or more, even though the sample proportion
was only 0.11.
(c) Finding 2 defective circuits in the sample.
6. (a) False 2 CHAPTER 1
(b) True
(c) True
A good knowledge of the process that generated the data. 7.
8. (a) An observational study
(b) It is not well-justified. Because the study is observational, there could be differences between the groups other
than the level of exercise. These other differences (confounders) could cause the difference in blood pressure.
9. (a) A controlled experiment
(b) It is well-justified, because it is based on a controlled experiment rather than an observational study.
Section 1.2
1. False
No. In the sample 1, 2, 4, the mean is 7/3, which does not appe 2. ar at all.
No. In the sample 1, 2, 4, the mean is 7/3, which does not appe 3. ar at all.
No. The median of the sample 1, 2, 4, 5 is 3. 4.
The sample size can be any odd number. 5.
Page 2 SECTION 1.2 3
Yes. For example, the list 1, 2, 12 has an average of 5 and a st 6. andard deviation of 6.08.
Yes. If all the numbers in the list are the same, the standar 7. d deviation will equal 0.
The mean increases by $50; the standard deviation is uncha 8. nged.
The mean and standard deviation both increase by 5%. 9.
10. (a) Let /u1D44B1,...,/u1D44B100denote the 100 numbers of occupants.
100/u⎪i2211.s1
/u1D456=1/u1D44B/u1D456= 70(1)+15(2)+10(3)+3(4)+2(5) = 152
/u1D44B=∑100
/u1D456=1/u1D44B/u1D456
100=152
100= 1.52
(b) The sample variance is
/u1D4602=1
99/pare⎪⎨eft.s4100/u⎪i2211.s1
/u1D456=1/u1D44B2
/u1D456−100/u1D44B2/pare⎪rig⎧t.s4
=1
99[(70)12+(15)22+(10)32+(3)42+(2)52−100(1.522)]
0=.87838
The standard deviation is /u1D460=√
/u1D4602= 0.9372.
Alternatively, the sample variance can be computed as
/u1D4602=1
99100/u⎪i2211.s1
/u1D456=1(/u1D44B/u1D456−/u1D44B)2
=1
99[70(1−1 .52)2+15(2−1 .52)2+10(3−1 .52)2+3(4−1 .52)2+2(5−1 .52)2]
0=.87838
(c) The sample median is the average of the 50th and 51st value when arranged in order. Both these values are
equal to 1, so the median is 1.
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