The hypothetical data below are from a toxicity study designed to measure the effectiveness of different doses of a pesticide on mosquitoes. The table below summarizes the concentration of the pesticide, the sample sizes, and the number of critters dispatched. 

a. Make a scatterplot of the proportions of mosquitoes killed versus the pesticide concentration.

b. Using the techniques introduced in this section, calculate  for each of the concentrations and fit the line y =a + b(Concentration). What is the sig nifi cance of a positive slope for this line?

c. The point at which the dose kills 50% of the pests is sometimes called LD50, for “Lethal dose 50%.” What would you estimate to be LD50 for this pesticide when used on mosquitoes?

Concentr 0.10 0.15 0.20 0.30 0.50 0.70 0.95 tion (g/cc) Number of 48 52 56 51 4753 51 mosquitoes Number 10 3 25 31 39 51 49 killed