The peak overpressure expected as a result of the explosion of a tank in a plant is approximated by the following equation:

\[\log P=6.0-1.8 \log r \]

where \(P\) is the overpressure in psi and \(r\) is the distance from the blast in feet. The plant employs 50 people who work in an area from 10 to \(500 \mathrm{ft}\) from the blast. Assume that the population density is constant in the work area.

a. Estimate the fraction of fatalities at 10, 100,250, and \(500 \mathrm{ft}\) using a probit equation.

b. Calculate the individual risk at each location in part (a) in \(\mathrm{yr}^{-1}\). Assume a frequency of the initiating event of \(10^{-4}\) per year.

c. Plot the risk contours.