The Department of Health encourages elderly people to have a flu vaccination each year.

The Department of Health encourages elderly people to have a flu vaccination each year. The vaccination reduces the likelihood of getting a flu from 40% to 10%. If 45% of the elderly people visiting the doctor have the vaccination, find the probability that an elderly person chosen at random had the vaccination, given that they get flu.

A disease is known to affect 1 in 10,000 people. It can be fatal, but it is treatable if it is detected early. A screening test for the disease shows a positive result for 99% of people with the disease. The test shows positive for 2% of people who do

A disease is known to affect 1 in 10,000 people. It can be fatal, but it is treatable if it is detected early. A screening test for the disease shows a positive result for 99% of people with the disease. The test shows positive for 2% of people who do not have the disease. For a population of one million people, how many would you expect to test positive?

A combination lock has 60 different positions. To open the lock, the dial is turned to a certain number in the clockwise direction, then to a number in the counterclockwise direction, and finally to a third number in the clockwise direction.

A combination lock has 60 different positions. To open the lock, the dial is turned to a certain number in the clockwise direction, then to a number in the counterclockwise direction, and finally to a third number in the clockwise direction. If successive numbers in the combination cannot be the same, how many different combinations are possible?

A bag contains 20 tennis balls, of which four are defective. If two balls are selected at random from the bag, what is the probability that both are defective?

A bag contains 20 tennis balls, of which four are defective. If two balls are selected at random from the bag, what is the probability that both are defective?

According to the theory of genetics a certain cross of guinea pigs will result in red, black and white offspring in the ratio 8:4:4. Find the probability that among 8 such offspring 5 will be red, 2 black and 1 white.

According to the theory of genetics a certain cross of guinea pigs will result in red, black and white offspring in the ratio 8:4:4. Find the probability that among 8 such offspring 5 will be red, 2 black and 1 white.