Worksheet #5 Solutions (75) Pts

Name: ______Lab Section: ______

Use the information in the following setting to answer questions 1-6:

A local merchant’s association would like to estimate the average length of time that patrons remain parked at a local parking garage. A SRS of garage users was collected during the summer months and their parking time was recorded (minutes). The descriptive output follows in Output 1.


1) The t-value required to compute a 95% margin of error is: [3 pts]

t = 1.984

2) The 95% margin of error is: [5 pts]

E = 1.984(0.243) = 0.482


3) The point estimate for the true average parking time for all garage users is: [2 pts]

4) The 95% CI for the true average parking time for all garage users is: [5 pts]

152 ± 0.482 = (151.52, 152.48) min

5) The English interpretation of this interval is: [5 pts]

We are 95% confident that the true average parking time for garage users is between 151.52 and 152.48 minutes


6) A city official makes the claim that users of the garage park there for 2 hours on average.

A) Construct the interval diagram that corresponds to your CI computed in Problem 4 [4 pts]


B) The appropriate null/alternative hypothesis pair associated with this setting is:

Ho: m = 120 [2 pts]

Ha: m ¹ 120 [2 pts]

C) Locate the hypothesized value on the CI diagram [1 pt]

[Note: be sure your units match!]

D) The statistical decision is: [1 pts]

Reject Ho

E) The English interpretation is: [5 pts]

At a significance level of 0.05 we can conclude that the average parking time is not 120 minutes. Based on our interval, people are parking longer than 2 hours.

Use the information in the following setting to answer questions 7-13:

One of the more controversial issues in the biotechnology arena is that of human cloning. Many people have significant concerns regarding others genetically replicating themselves. A recent Gallup poll revealed that, of 1012 randomly selected adults only 91 reported that human cloning was ethically and morally “OK”. Let a = 0.01. Do these results provide enough evidence to support a claim that fewer than 12% of the population view human cloning as “OK”?

7) Ho: p 0.12 [3 pts]

Ha: p < 0.12 [3 pts]

8) a = 0.01 Test Type: 1 tail? z-crit = - 2.326 [2 pts each]


9) Draw the decision curve: [5 pts]

10) z-calc = [5 pts]


11) Label z-calc on the decision curve: [3 pts]

12) The statistical decision is: [2 pts]

Reject Ho

13) The English interpretation is: [3 pts]

At a = 0.01 we can conclude that the proportion of adults who feel that human cloning is ethically and morally “OK” is less than 12%

14) The P-value is: [4 pts]

This is a Type I standard normal problem. We want

Pr{z -2.94} = 0.0016

15) Draw a diagram that **CLEARLY** illustrates the P-value: [6 pts]

Rick Gumina STCC201 Worksheet5_Sol_S04.doc

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