The water level of a certain reservoir is depleted at a constant rate of 1000 units daily. The reservoir is refilled by random rainfalls. Rainfalls occur according to a Poisson process with rate 0.3 per day. The amount of water added to the reservoir by a rainfall is exactly 5000 units with probability 0.6 or exactly 8000 units with probability 0.4. The present water level is just shy of 5000 units.

Required:
a. What is the probability the reservoir will be empty after five days?
b. What is the probability the reservoir will be empty sometime within the next ten days?

Respuesta :

Answer:

a. Probability the reservoir will be empty after five days

e-1.5 + 0.6 e-1.5 e-1.5

b. Probability the reservoir will be empty sometime within the next ten days

Probability of rain falls in next ten days = 10 x 0.4

                                                                      =4

Step-by-step explanation:

The water level of the reservoir is depleted at a constant rate of 1000 units daily.

Rainfalls occur to the Poisson process with a rate of 0.3 per day.

a) Probability the reservoir will empty after five days is when there is no rain in the next five days.

Rainfall rate = 0.3 per day

Expected rain fall = 5 x 0.3 =1.5

Mean = µ =1.5, rain fall =x = 0

By using Poisson distribution formula, we get

P (empty) =p( empty at 5 day) + p (1.5 x 5000) x p(empty in 5 day)

                = e-1.5 + 0.6 e-1.5 e-1.5

b)

The next ten days reservoir will be empty if there will be no rain.

There will be one rain of 5000 units in the next ten days.

Probability of rain falls in next ten days = 10 x 0.4

                                                                      =4

Hence, four is the probability of rain falls in the next ten days