Respuesta :
Answer:
0.7788 = 77.88% probability that more than three customers arrive in 10 minutes
Step-by-step explanation:
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) = \int\limits^a_0 {f(x)} \, dx[/tex]
Which has the following solution:
[tex]P(X \leq x) = 1 - e^{-\mu x}[/tex]
The probability of finding a value higher than x is:
[tex]P(X > x) = 1 - P(X \leq x) = 1 - (1 - e^{-\mu x}) = e^{-\mu x}[/tex]
In this question, we have that:
The time between arrivals of customers at an automatic teller machine is an exponential random variable with a mean of 4 minutes, and we have three customers, which means that [tex]m = 3*4 = 12, \mu = \frac{1}{12} = 0.0833[/tex]
(a) What is the probability that more than three customers arrive in 10 minutes
This is P(X > 3). So
[tex]P(X > 3) = e^{-0.0833*3} = 0.7788[/tex]
0.7788 = 77.88% probability that more than three customers arrive in 10 minutes
