Deck 15: Probability Models

Question 1

The blood drive has a total of 150 donors.Assuming this is a typical number of donors for a
school blood drive, what would be the mean and standard deviation of the number of donors
who have Type B blood?

Answer 1

The owner had 275 customers that day.Assuming this was a typical day for his store, what
would be the mean and standard deviation of the number of customers who buy specialty
clothes for their pet each day?

Question 2

What is the probability that at least 2 of the first 10 blood donors has Type B blood?

Answer 2

What is the probability that at least 3 of the first 10 customers buy specialty clothes for their
pet? Show work.

Question 3

What is the probability that the tenth blood donor is the first donor with Type B blood?

Answer 3

What is the probability that she does not sell a garment until the seventh customer? Show
work.

Question 4

Surprised by the low number of Type B blood donors at the blood drive, the American Red
Cross wonders if the 11% estimate was too high for your area.How many Type B blood
donors would it take to convince you that this estimate might be too high? Justify your answer.

Question 5

What is the probability that exactly 2 of the first 20 blood donors have Type B blood?

Question 6

How many blood donors should the American Red Cross expect to collect from until it gets a
donor with Type B blood?