Answer:
1. c. Poisson
2. 0.9592 = 95.92% probability that in any one minute at least one purchase is made.
3. 0.0017 = 0.17% probability that no one makes a purchase in the next 2 minutes.
Explanation:
We have only the mean, which means that the Poisson distribution is used to solve this question, and thus the answer to question 1 is given by option c.
Poisson distribution:
In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:
![P(X = x) = (e^(-\mu)*\mu^(x))/((x)!)](https://img.qammunity.org/2022/formulas/mathematics/college/fc9bfg9bauetugxxr4o8egdqz83cs0jk74.png)
In which
x is the number of sucesses
e = 2.71828 is the Euler number
is the mean in the given interval.
Mean of 3.2 minutes:
This means that
, in which n is the number of minutes.
2. What is the probability that in any one minute at least one purchase is made?
, so
.
This probability is:
![P(X \geq 1) = 1 - P(X = 0)](https://img.qammunity.org/2022/formulas/mathematics/college/xnao519qpqw5plhnsmdyk19y4c62sua2t9.png)
In which
![P(X = x) = (e^(-\mu)*\mu^(x))/((x)!)](https://img.qammunity.org/2022/formulas/mathematics/college/fc9bfg9bauetugxxr4o8egdqz83cs0jk74.png)
![P(X = 0) = (e^(-3.2)*3.2^(0))/((0)!) = 0.0408](https://img.qammunity.org/2022/formulas/mathematics/college/820vreh7ji2te5tetgaa3ua7g75w9itxp5.png)
So
![P(X \geq 1) = 1 - P(X = 0) = 1 - 0.0408 = 0.9592](https://img.qammunity.org/2022/formulas/mathematics/college/5mqpkecefel2tjbjz0vmebz6lxzkewcrp8.png)
0.9592 = 95.92% probability that in any one minute at least one purchase is made.
3. What is the probability that no one makes a purchase in the next 2 minutes?
2 minutes, so
![n = 2, \mu = 3.2(2) = 6.4](https://img.qammunity.org/2022/formulas/mathematics/college/5mzizrwugtooy0kpu45975vzv0qs2z2i8o.png)
This probability is P(X = 0). So
![P(X = x) = (e^(-\mu)*\mu^(x))/((x)!)](https://img.qammunity.org/2022/formulas/mathematics/college/fc9bfg9bauetugxxr4o8egdqz83cs0jk74.png)
![P(X = 0) = (e^(-6.4)*6.4^(0))/((0)!) = 0.0017](https://img.qammunity.org/2022/formulas/mathematics/college/lqh8o4137y92hlg6fktk7rm890jdqou962.png)
0.0017 = 0.17% probability that no one makes a purchase in the next 2 minutes.