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The number of wrongly dialed phone calls you receive can be modeled as a Poisson process with the rate of one per month. For simplicity, ass
Question
The number of wrongly dialed phone calls you receive can be modeled as a Poisson process with the rate of one per month. For simplicity, assume there are four weeks in one month.
a. Find the probability that it will take between two and three weeks to get the first wrongly dialed phone call.
b. Suppose that you have not received a wrongly dialed phone call for two weeks. Find the expected value and variance of the additional time until the next wrongly dialed phone call.
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Mathematics
4 years
2021-08-29T00:23:41+00:00
2021-08-29T00:23:41+00:00 1 Answers
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Answer:
Part a: P (14/30<x<21/30) = 0.1304
Partb: Expected value= Variance= 0.866
Step-by-step explanation:
The poisson distribution is given by
P(x)= μˣ . e^ -u/ x!
In this question
x= 1
n= 30
μ= 1/30
P(x)= μˣ . e^ -u/ x!
= 0.333. e⁻¹/³⁰/1!
= 0.33*0.967/1
= 0.32208
For 2 weeks
x= 14
n= 30
μ= 14/30
P(x)= μˣ . e^ -u/ x!
= 0.467. e⁻¹⁴/³⁰/14!
= 0.467*0.627/14!
= 0.29285/14!
=3.359*e⁻¹²
= 0.0139
For 3 weeks
x= 21
n= 30
μ= 21/30
P(x)= μˣ . e^ -u/ x!
= 0.7* e⁻²¹/³⁰/21!
= 0.7*0.4965/21!
= 0.3476/21!
=6.8037*e⁻²¹
= 0.11648
Part a:
P (14/30<x<21/30) = P (x= 14/30) + P (x=21/30)
(0.0139 +0.11648) =0.1304
Part b:
Probability of Not receiving the call for two weeks = 1- P (x= 14/30)=0.9861
The mean and the variance of the Poisson distribution are equal to μ
For x= 14
Expected value not getting wrongly dialed phone call in 2 week = μ= 1-14/30 = 1-0.467= 0.533
Variance of not getting wrongly dialed phone call in 2 week= μ=1- 14/30= 1-0.467= 0.533
Expected value of the additional time until the next wrongly dialed phone call
Expected value not getting wrongly dialed phone call in 2 weeks + Expected value of next wrongly dialed phone call in a month
= 0.533+0.33=0.866
Variance of the additional time until the next wrongly dialed phone call
= Expected value of the additional time until the next wrongly dialed phone call =0.866