Intensive care units (ICUs) generally treat the sickest patients in a hospital. ICUs are often the most expensive department in a hospital because of the specialized equipment and extensive training required to be an ICU doctor or nurse. Therefore, it is important to use ICUs as efficiently as possible in a hospital. According to a 2017 large-scale study of elderly ICU patients, the average length of stay in the ICU is 3.4 days (Critical Care Medicine journal article). Assume that this length of stay in the ICU has an exponential distribution. Do not round intermediate calculations.

a. What is the probability that the length of stay in the ICU is one day or less (to 4 decimals)?

b. What is the probability that the length of stay in the ICU is between two and three days (to 4 decimals)?

c. What is the probability that the length of stay in the ICU is more than five days (to 4 decimals)?

Respuesta :

Using the exponential distribution, it is found that there is a:

a) 0.2548 = 25.48% probability that the length of stay in the ICU is one day or less.

b) 0.1415 = 14.15% probability that the length of stay in the ICU is between two and three days.

c) 0.2298 = 22.98% probability that the length of stay in the ICU is more than five days.

Exponential distribution:

The exponential probability distribution, with mean m, is described by the following equation:  

[tex]f(x) = \mu e^{-\mu x}[/tex]

In which [tex]\mu = \frac{1}{m}[/tex] is the decay parameter.

The probability that x is lower or equal to a is given by:  

[tex]P(X \leq x) = 1 - e^{-\mu x}[/tex]

The probability of finding a value higher than x is:

[tex]P(X > x) = e^{-\mu x}[/tex]

In this problem, the mean is of 3.4 days, hence, the decay parameter is:

[tex]\mu = \frac{1}{3.4}[/tex]

Item a:

[tex]P(X \leq 1) = 1 - e^{-\frac{1}{3.4}} = 0.2548[/tex]

0.2548 = 25.48% probability that the length of stay in the ICU is one day or less.

Item b:

[tex]P(X \leq 2) = 1 - e^{-\frac{2}{3.4}} = 0.4447[/tex]

[tex]P(X \leq 3) = 1 - e^{-\frac{3}{3.4}} = 0.5862[/tex]

[tex]P(2 \leq X \leq 3) = 0.5862 - 0.4447 = 0.1415[/tex]

0.1415 = 14.15% probability that the length of stay in the ICU is between two and three days.

Item c:

[tex]P(X > 5) = e^{-\frac{5}{3.4}} = 0.2298[/tex]

0.2298 = 22.98% probability that the length of stay in the ICU is more than five days.

A similar problem is given at https://brainly.com/question/17039711