Statistics / Mr. Hansen
3/10/2004


Check one:

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c Regular time (36 minutes)
c Extended time (54 minutes)

Warm-Up Quiz on Chapters 11 and 12

Instructions and Scoring.

  • Show all work and answers on separate sheets.
  • Show as much work as time provides. Justify all steps except for algebraic simplification or z or t area calculations. The calculation of the value of z or t should be shown. Also, for full credit, you should show the details of s.e. and m.o.e. calculations to the extent possible.
  • You will not earn full credit for a correct answer without adequate justification, or a correct answer without correct notation.

 

 

 

 

 

Returning to our example of Qvale and Ferrari owners, suppose that we have an SRS of 250 male owners of each type of automobile. The Qvale owners sampled have a mean height of 69 inches with s.d. of 1.2 inches, while the Ferrari owners sampled have a mean height of 70.5 inches with s.d. of 1.3 inches.

 

 

1.

Is the difference in heights statistically significant?

 

 

2.

Compute a 95% confidence interval for the difference between the mean heights of the two types of owners.

 

 

3.

If both sets of results are normally distributed, compute the probability that a randomly selected male Ferrari owner is taller than a randomly selected male Qvale owner.

 

 

4.

In the samples, 14.4% of the male Qvale owners and 60.8% of the male Ferrari owners are supercilious. Compute an 80% confidence interval for the amount by which the incidence of superciliousness is greater among male Ferrari owners than among male Qvale owners.

 

 

5.

Is there evidence at the 5% significance level to support the claim that Ferrari owners are more likely than Qvale owners to be supercilious?