A boat is being lowered into a river from a dock using a chain attached to a pulley on the tip of a 20 ft boom. If the tip of the boom is 16 ft above the water and the chain is being let down at a rate of .5 ft/sec, what is the rate of change of the distance between the boom and the center of the boat?

Over the course of the school year, you keep track of how much snow falls on a given day and whether it was a snow day. your data indicates that of twenty-one days with less than three inches of snow, five were snow days, while of the eight days with more than three inches of snow, six were snow days. if all you know about a day is that it is snowing, what is the probability that it will be a snow day?