Intro to Stats – hw#25
Make a probability tree, and then answer the following questions for each senario.
(1)
A drug test will correctly detect steroid use 80% of the time. Further, 10% of all rugby players use
steroids. If you randomly choose someone on the rugby team
(a)
(b)
(2)
A drug test will correctly detect steroid use 70% of the time. Further, 20% of all rugby players use
steroids. If you randomly choose someone on the rugby team
(a)
(b)
(3)
What is the probability that if he has tested positive that he used steroids?
What is the probability if he has tested negative and he did not use steroids?
As accounts manager in your company, you classify 80% of your customers as "good credit" and
the rest as "risky credit" depending on their credit rating. Customers in the "risky" category allow
their accounts to go overdue 60% of the time on average, whereas those in the "good" category
allow their accounts to become overdue only 10% of the time
(a)
(b)
(4)
What is the probability that if he has tested positive that he used steroids?
What is the probability if he has tested negative and he did not use steroids?
What percentage of overdue accounts are held by customers in the "risky credit" category?
Given that a customer is not overdue, what is the probability that they are one of your
“good” customers?
As accounts manager in your company, you classify 70% of your customers as "good credit" and
the rest as "risky credit" depending on their credit rating. Customers in the "risky" category allow
their accounts to go overdue 50% of the time on average, whereas those in the "good" category
allow their accounts to become overdue only 20% of the time
(a)
(b)
What percentage of overdue accounts are held by customers in the "risky credit" category?
Given that a customer is not overdue, what is the probability that they are one of your
“good” customers?
Answer
(1)
(2)
(3)
(4)
Put your final answer in the box in front of the question
Steroids on the rugby team.
(a)
What is the probability that if he has tested positive that he used steroids?
(b)
What is the probability if he has tested negative and he did not use steroids?
Steroids on the rugby team.
(a)
What is the probability that if he has tested positive that he used steroids?
(b)
What is the probability if he has tested negative and he did not use steroids?
Accounts "risky" go overdue
(a)
What percentage of overdue accounts are held by customers in the "risky credit" category?
(b)
Given that a customer is not overdue, what is the probability that they are one of your
“good” customers?
Accounts "risky" go overdue
(a)
What percentage of overdue accounts are held by customers in the "risky credit" category?
(b)
Given that a customer is not overdue, what is the probability that they are one of your
“good” customers?