Problem of the day for Tuesday, December 20

Yesterday's problem

December 16 hints and answers

Another race! Alice is 100 meters from Bill and Bill is 300 meters from Chelsea. They all move to the right at constant speeds. In 6 minutes, Alice overtakes Bill, and in another 6 minutes, Alice overtakes Chelsea. How many minutes did it take for Bill to overtake Chelsea?


Making a picture will certainly help. The thing that makes this problem tricky is that while Alice is catching up to Bill, Chelsea is moving the whole time. So you have to account for her movements somehow, too.

As you did yesterday, you might employ the strategy of assuming that the three move at specific speeds, consistent with the data in the problem, then do a more general case.

As always, be sure to explain the work you did to arrive at your answers!