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 researcher counts gypsy moth (Lymantria dispar) egg masses in 47 quarter-acre plots and finds an average of 34.2 egg masses with a standard deviation of 14.8. A survey from the previous season found an average of 27.1 egg masses per quarter-acre. Does the new data support the claim that the level of infestation (as measured by the average number of egg masses per quarter acre) is higher this year?
Problem 2
Analysis of a sample of 45 deer ticks (Ixodes scapularis) from wooded area reveals the presence of the Ehrlichiosis pathogen (the Ehrlichia chaffeensis bacteria) in 17 ticks.
A sample of 37 ticks taken three years earlier in the same area had 9 ticks test positive for the
bacteria. Does this data support the claim that the prevalence of the Ehrlichiosis pathogen has risen over the last three years?
Problem 3
A survey of 190 randomly selected Eucalyptus trees in Pacific Grove, California finds
an average of 13.5 monarch butterfly (Danus plexippus) egg masses per tree.
Historical records indicate that 3.4 is a reliable estimate the standard deviation of measurements of this kind. Construct 95 and 99 percent confidence intervals for the average number of
monarch butterfly egg masses per tree.