The probability that on a randomly selected day she will have no messages 
Further Explanation:
The random variable X follows Poisson distribution.

Here,
represents the Poisson parameter.
The mean of the Poisson parameter is 
The variance of the Poisson parameter is 
The formula for the probability of Poisson distribution can be expressed as follows,

Given:
The number of messages follows Poisson distribution.
The value of
is 
Explanation:
A statistics professor receives an average of five e-mail messages per day from students.
The mean of the message is 5.
The probability that on a randomly selected day she will have no messages can be obtained as follows,

The probability that on a randomly selected day she will have no messages 
Learn more:
1. Learn more about normal distribution brainly.com/question/12698949
2. Learn more about standard normal distribution brainly.com/question/13006989
3. Learn more about confidence interval of meanhttps://brainly.com/question/12986589
Answer details:
Grade: College
Subject: Statistics
Chapter: Poissondistribution
Keywords: statistics professor, receives, average, five e-mail, message, students, messages per day, Poisson distribution, probability, randomly selected, no message, parameter, probability formula, number of message.