A man hikes up a mountain, and starts hiking at 2:00 in the afternoon on a Friday. He does not hike at the same speed (a constant rate), and stops every once in a while to look at the view. He reaches the top in 4 hours. After spending the night at the top, he leaves the next day on the same trail at 2:00 in the afternoon. Coming down, he doesn't hike at a constant rate, and stops every once in a while to look at the view. It takes him 3 hours to get down the mountain.
Q: What is the probability that there exists a point along the trail that the hiker was at on the same time Friday as Saturday? You can assume that the hiker never backtracked.
A boy, a girl and a dog go for a 10 mile walk. The boy and girl can walk at 2 mph and the dog can trot at 4 mph. They also have a bicycle which only one of them (including the dog!) can use at a time. When riding, the boy and girl can travel at 12 mph while the dog can pedal at 16 mph. What is the shortest time in which all three can complete the trip?
A bug walks down a rubber band which is attached to a wall at one end and a car moving away from the wall at the other end. The car is moving at 1 m/sec while the bug is only moving at 1 cm/sec. Assuming the rubber band is uniformly and infinitely elastic, will the bug ever reach the car?
Snow starts falling before noon on a cold December day. At noon a snow plow starts plowing a street. It travels 1 mile in the first hour, and 1/2 mile in the second hour. What time did the snow start falling?? You may assume that the plow's rate of travel is inversely proportional to the height of the snow, and that the snow falls at a uniform rate.
n people each know a different piece of gossip. They can telephone each other and exchange all the information they know (so that after the call they both know anything that either of them knew before the call). What is the smallest number of calls needed so that everyone knows everything? |
