Your math is not correct on this. You have stated the rate of deaths per mile, not the probability of not dying per mile, e.g. if 2 people died per mile, then the probability of dying per mile is not 200%.
I believe this should follow a Poisson distribution, i.e.f(k;m) = ((rm)^k * e^-(rm)) / k!, where k is the number of deaths, m is the miles traveled, and r is the deaths per mile. Then, the probability of dying after traveling m miles is 1 - f(0;m), i.e. the probability of no deaths occurring. Thus, the probability of dying when traveling 10^6 miles is 1 - e^-(7.3 / 10^9 * 10^6) = 0.727%.
Your math is not correct on this. You have stated the rate of deaths per mile, not the probability of not dying per mile, e.g. if 2 people died per mile, then the probability of dying per mile is not 200%.
I believe this should follow a Poisson distribution, i.e.f(k;m) = ((rm)^k * e^-(rm)) / k!, where k is the number of deaths, m is the miles traveled, and r is the deaths per mile. Then, the probability of dying after traveling m miles is 1 - f(0;m), i.e. the probability of no deaths occurring. Thus, the probability of dying when traveling 10^6 miles is 1 - e^-(7.3 / 10^9 * 10^6) = 0.727%.