Some previous studies have shown a relationship betweenemergency room admissions

Some previous studies have shown a relationship betweenemergency room admissions per day and level of pollution on a givenday. A small local hospital finds that the number of admissions tothe emergency ward on a single low-pollution day follows a Poissondistribution with mean=2.0 admissions per day and a high-pollutionday follows a Poisson distribution with mean=4 admissions per day.Suppose each admitted person to the emergency ward stays there forexactly 1 day and is then discharged. On a random day during theyear what is the probability there will be 4 admissions to theemergency ward assuming there are 345 normal-pollution days and 20high-pollution days?