"conservationists have despaired over destruction of tropical rain forest by logging, clearing, and burning." these words begin a report on a statistical study of the effects of logging in borneo. here are data on the number of tree species in 12 unlogged forest plots and 9 similar plots logged 8 years earlier: unlogged 22 18 22 20 15 21 13 13 19 13 19 15 logged 17 4 18 14 18 15 15 10 12 use the data to give a 90% confidence interval for the difference in mean number of species between unlogged and logged plots. compute degrees of freedom using the conservative method.

Nthe opening scene of the movie raiders of the lost ark, indiana jones replaces a golden statue with a bag of sand. the platform on which the statue is placed is designed to detect the mass of the statue. if the bag of sand has a different mass than the statue, then a mechanism triggers and destruction ensues. the density of gold is about 20\text{ g/cm}^320 g/cm 3 20, space, g, slash, c, m, start superscript, 3, end superscript. the density of sand can be estimated at 2.5\text{ g/cm}^32.5 g/cm 3 2, point, 5, space, g, slash, c, m, start superscript, 3, end superscript. the gold statue can be modeled as a cylinder with height 25\text{ cm}25 cm25, space, c, m and radius 8\text{ cm}8 cm8, space, c, m. in terms of \piπpi, what is the mass of sand indiana jones needs to avoid triggering the mechanism?