A hotel experienced an outbreak of Pseudomona dermatis among its guests. Physicians suspected the source of infection to be the hotel whirlpool-spa. The data in the table give the number of female...

A hotel experienced an outbreak of Pseudomona dermatis among its guests. Physicians suspected the source of infection to be the hotel whirlpool-spa. The data in the table give the number of female guests and the number infected by categories of time (minutes) spent in the whirlpool.

(a) Can the incidence of infection (number infected/number exposed) be characterized by a linear regression on time spent in the whirlpool? Use the midpoint of the time interval as the independent variable. Estimate the intercept and the slope, and plot the regression line and the data.

(b) Review each of the basic assumptions of least squares regression and comment on whether each is satisfied by these data.