In: Statistics and Probability
Assume a Poisson random variable has a mean of 9 successes over
a 126-minute period.
a. Find the mean of the random variable, defined
by the time between successes.
b. What is the rate parameter of the appropriate exponential distribution? (Round your answer to 2 decimal places.)
c. Find the probability that the time to
success will be more than 59 minutes. (Round intermediate
calculations to at least 4 decimal places and final answer to 4
decimal places.)
Answer:
Given that:
Assume a Poisson random variable has a mean of 9 successes over a 126-minute period.
a) Find the mean of the random variable, defined by the time between successes.
It is given that, a Poisson random variable has a mean of 9 successes over a 126 minute period.
That is
Since the successes follow Poisson distribution, the time between successes has an exponential distribution.
The mean of the random variable defined by the time between successes is
Thus,the mean of the random variable, defined by the time between successes is 14 minutes
b) What is the rate parameter of the appropriate exponential distribution?
In exponential distribution, is the rate parameter which is the inverse of the mean
The required rate parameter is
Thus, the rate parameter of the appropriate exponential distribution is 0.07
c) Find the probability that the time to success will be more than 59 minutes
The cumulative distribution function of Exponential distribution is
The probability that the time to success wil be more than 59 minutes is
Thus,the probability that the time to success will be more than 59 minutes is 0.0161