I'm stuck with a very strange problem at hand and need an urgent solution.

A speciality hospital caters to patients a particular type of disease only. There are 4 types of manifestations of the disease which take different time to cure.

Type No. of days of stay in the Hospital (bed occupancy days)

A 3

B 7

C 15

D 24

What should be the number of beds in the hospital so that 99% of the cases, a patient is not denied admittance?

Quick solutions will be highly appreciated. I have a presentation in 3 hours!

Thanks in advance !