Researchers have studied the ecology of ponds in rural Bangladesh. Of particular interest in such studies are the zooplankton, phytoplankton, and copepod counts (per liter of water) in these ponds. Copepods are a particular type of zooplankton that are thought to be a natural reservoir of cholera bacteria, but copepod counts can be difficult to obtain in laboratory analyses; total zooplankton counts are easier to obtain. It is also believed that copepod counts will be related to phytoplankton counts since copepods feed on phytoplankton.
The data here show zooplankton, phytoplankton, and copepod counts for 100 water samples from ponds in rural Bangladesh.

a. Find the estimated least-squares equation for the regression of copepod count on zooplankton count.
b. Test the null hypothesis that the true slope is zero, at the α = .05 significance level. Interpret your result.
c. Find a 95% confidence interval for the true slope in part (a). Interpret your result.
d. Find the estimated least-squares equation for the regression of copepod count on phytoplankton count.
e. Test the null hypothesis that the true slope in part (d) is zero, at the α = .05 significance level. Interpret your result.