STATISTICS
It is known that increased reproductions leads to reduced longevity for female fruitflies. Patridge and Farquhar (1981) studied whether the same phenomenon held for male fruitflies. The data are also discussed in Hanley and Shapiro (1994). The experiment set up five treatment groups, each consisting of 25 randomly assigned male fruitflies. The males in one treatment were housed with eight virgin females per day. In another treatment, the males were housed with one virgin female day. There were three control groups: males housed with eight newly impregnated females, housed with one newly impregnated female, and housed alone. (Newly inseminated females will not usually mate within two days). The data are contained in the file fruitfly, with a row for each male in the following format: Column 1: the number of females Column 2: the type of female—0 denoting newly pregnant, 1 denoting virgin, and 9 when there were no females Column 3: lifespan in days Column 4: length of thorax (mm), which is fixed at birth Column 5: percentage of time spent sleeping a. Calculate summary statistics for lifespan in each group and compare. Display the data in parallel boxplots. Qualitatively, what do you conclude? b. Do the same for percentage of time spent sleeping. c. Make a scatterplot of lifespan versus thorax length. Is thorax length predictive of lifespan and did the randomization balance thorax length between the groups? d. Use the F test to test for differences in longevity between the groups. Use both Tukey’s method and the Bonferroni method to compare all pairs of means. Summarize your conclusions. e. Repeat the analysis using the Kruskal-Wallis test and the Bonferroni method. f. How does the availability of virgin females affect the sleep of male fruitflies?
ENVIRONMENTAL SCIENCE
Write your answer to each part clearly. Support your answers with relevant information and examples. Where calculations are required, show your work. The City of Philadelphia recently replaced one out of every 10 trash bins with solar-powered trash compactors. The compactor is an enclosed unit with a door that opens for trash disposal. The compactor automatically detects when the bin is full and uses a solar-powered mechanical crusher to compact the contents. When the compactor needs to be emptied, it sends an electronic signal. Use of solar-powered compactors has increased the capacity of public trash bins and has reduced the number of trash collection visits to each bin from 17 times per week to 5 times per week. (a) Describe four positive externalities of installing solar-powered trash compactors. (b) Describe six cradle-to-grave components of solar-powered trash compactors. (c) Suggest one way that the installation of solar powered trash compactors can reverse the effects of urban blight. (d) The price of a regular trash bin is $300, and it has a lifespan of 20 years. The price of a solar powered trash compactor is$4,000, and it has a lifespan of 10 years; it also requires approximately $150 in maintenance costs each year. On average, a trash collection visit costs$5 in fuel and $20 in employee salary. Based on this information, are solar-powered trash compactors economically beneficial? (e) Describe two ways that you might determine if solar-powered trash compactors are environmentally beneficial.