The average polar bear weighs 1,200 pounds. the average grizzly bear weighs 800 pounds. the average black bear weighs 400 pounds. the average polar bear weighs how many times more than the average black bear?

Among the most famous of all meteor showers are the perseids, which occur each year in early august. in some areas the frequency of visible perseids can be as high as 40 per hour. given that such sightings are poisson events, calculate the probability that an observer who has just seen a meteor will have to wait at least five minutes before seeing another.