In: Statistics and Probability
Approximately 6.85 left-handed people are killed each day by using an object or machinery designed for right-handed people. Let X be the number of left-handed people killed this way in one day.
a. What values can X take? Why is this a Poisson situation? What is the parameter?
b. What is the probability that exactly 7 left-handed people will be killed using a right-handed object tomorrow?
c. What is the expected number of left-handed people killed using a right-handed object over the next week?
d. What is the standard deviation of the number of left-handed people killed using a right-handed object over the next week?
e. What is the probability that at least 2 left-handed people will be killed using a right-handed object tomorrow?
f. What is the probability that you will have to check more than 3 days until you find the first day which has at least 2 left-handed people killed using a right-handed object? What distribution are you using now and what is the parameter?
a)
Since any number of people can be killed in this way so X can take values 0, 1, 2, 3, ....
Since we have average number of people killed in this way is a day (in a specific time frame) so X has Poisson distribution. Here X has Poisson distribution with parameter .
b)
The probability that exactly 7 left-handed people will be killed using a right-handed object tomorrow is
c)
Since one week means 7 days so here X has Poisson distribution with parameter
So the expected number of left-handed people killed using a right-handed object over the next week is
d)
The standard deviation of the number of left-handed people killed using a right-handed object over the next week is
e)
f)
Here we need to use geometric distribution, let denoted by Y, with parameter p = 0.99169.
The probability that you will have to check more than 3 days until you find the first day which has at least 2 left-handed people killed using a right-handed object is