Problems

1.Suppose the historical average work week was 39.2 hours and SD was 4.8 hours as reported by the labor Dept. This year a study of 112 workers showed a mean of 38.5 hours. Test whether the workweek is the same or significantly shorter due to the recession. (Left tail). Use a .10 significance level.

a.Calculate the appropriate Z or T -----------------------------

b.What is the appropriate Critical value T or Z --------------------------------

c.Statistical conclusion----------------------------------------------------

d.Practical conclusion ---------------------------------------------------------------

2.A Shell oil company executive says (Claims) that a majority of workers - more than 50% - prefer a 10 hour four day work week over an 8 hour five day work week. Of a 105 worker sample, 67 said they prefer a 10-hour-4-day work-week. At alpha- significance level of 0.10 does this sample support the executive's suggestion (more than 50%, right tail)

e.Critical Value

f.What is the appropriate calculated test statistic T or Z

g.Statistical conclusion.Practical conclusion

3.The financial industry Earnings average per share last year were $3. This year, earnings per sharein 10 financial companies were as follows. Test the hypothesis that this year's earnings differ (higher or lower) from last year - two tail, at alpha (significance level) =.01

Data 1.92, 2.16, 3.63, 3.16, 4.10, 3.14, 2.20, 2.34, 3.10, 2.38

Hypothesis being tested : Mean=3

h.Critical Value T or Z

i.What is the appropriate

j.Statistical conclusion

k.Practical conclusion

4.A study showed that 110 of 200 people say that their major source of news is TV.

l.What would be a 99% confidence interval for the proportion?

m.What i s the appropriate sample size if you want to re-conduct that survey

5.Confidence Interval : A sample of 100 CNN viewers shows an average household income of 119 K and a standard deviation of 30k.

n.What would the 99% confidence interval of the mean be? ___________

o.What is an appropriate sample size?