MA145 Final Exam - Takehome Portion
For each of the problems below, use the MA145 technology guide to perform a statistical analysis.
You should justify your choice of method, including any assumptions made in the use of the method.
You should indicate whether a two-tailed, left-tailed, or right-tailed analysis is appropriate,
and, in hypothesis testing problems, state the null and alternative hypotheses.
If the problem does not specify a level of significance, you should choose one.
Problem 1
A political polling company questions a random sample 1000 likely voters in a large city and
discovers that 457 of them plan to vote for a certain candidate. Calculate a 99% confidence
interval for the proportion of votes that the candidate expects to receive.
Problem 2
In 2004 a sample of 90 Eucalyptus trees is selected at random in Pacific Grove, California and
the number monarch butterfly (Danus plexippus) egg masses found on each tree is counted.
In 2005, the process is repeated for the same 90 trees. The average difference in the egg mass
counts for each tree is recorded, and has a mean value of -3.2 with a standard deviation of 4.5.
Does this represent a statistically significant change in the number of egg masses per tree?
Problem 3
A contractor provides training in job search skills for unemployed workers. Nationally,
56% of people who go through similar programs find jobs within 3 months. In a sample of
85 workers trained by this contractor, 38 found jobs within 3 months. Test the claim that
this contractor's success rate matches the national average.