Fill This Form To Receive Instant Help

Help in Homework
trustpilot ratings
google ratings


Homework answers / question archive / 3

3

Statistics

3.7 The tensile strength of Portland cement is being studied. Four different mixing techniques can be used economically. A completely randomized experiment was conducted and the following data were collected:

Mixing Technique                                   Tensile Strength (Ib/in2)

1

3129

3000

2865

2890

2

3200

3300

2975

3150

3

2800

2900

2985

3050

4

2600

2700

2600

2765

 

 (a) Test the hypothesis that mixing techniques affect the strength of the cement. Use a = 0.05.

(b) Construct a graphical display as described in Section 3.5.3 to compare the mean tensile strengths for the four mixing techniques. What are your conclusions?

(c) Use the Fisher LSD method with a = 0.05 to make comparisons between pairs of means.

(d) Construct a normal probability plot of the residuals. What conclusion would you draw about the validity of the normality assumption?

(e) Plot the residuals versus the predicted tensile strength. Comment on the plot.

(f) Prepare a scatter plot of the results to aid the interpretation of the results of this experiment.

3.12. A pharmaceutical manufacturer wants to investigate the bioactivity of a. new drug. A completely randomized single-factor experiment was conducted with three dosage levels, and the following results were obtained.

Dosage                                                                       Observations

20g

24

28

37

30

30g

37

44

31

35

40g

42

47

52

38

 

 (a) Is there evidence to indicate that dosage level affects bioactivity? Use a = 0.05.

(b) If it is appropriate to do so, make comparisons between the pairs of means. What conclusions can you draw?

(c) Analyze the residuals from this experiment and comment on model adequacy.

3.28  An experiment was performed to investigate the effectiveness of five insulating materials. Four samples of each material were tested at an elevated voltage level to accelerate the time to failure. The failure times (in minutes) are shown below:

Material                                                                           Failure Time (minutes)

1

110

157

194

178

2

1

2

4

18

3

880

1256

5276

4355

4

495

7040

5307

10,050

5

7

5

29

2

 

 (a) Do all five materials have the same effect on mean fail-ure time?

(b) Plot the residuals versus the predicted response. Construct a normal probability plot of the residuals. What information is conveyed by these plots?

(c) Based on your answer to part (b) conduct another analysis of the failure time data and draw appropriate conclusions.

Option 1

Low Cost Option
Download this past answer in few clicks

24.99 USD

PURCHASE SOLUTION

Already member?


Option 2

Custom new solution created by our subject matter experts

GET A QUOTE