Puzzles from the Math Midway
The Ruler That Missed The Mark Concluded
Working together, Sally and Nate filled in the rest of the table, so that it looked like.
| To measure | Measure from: | and measure to: |
| 1 inch | left end of ruler | 1-inch mark |
| 2 inches | 1-inch mark | 3-inch mark |
| 3 inches | left end of ruler | 3-inch mark |
| 4 inches | 3-inch mark | 7-inch mark |
| 5 inches | 3-inch mark | right end of ruler |
| 6 inches | 1-inch mark | 7-inch mark |
| 7 inches | left end of ruler | 7-inch mark |
| 8 inches | left end of ruler | right end of ruler |
When they were done, Nate was feeling much better. "I can't wait until the teacher asks us to measure a six-inch triangle -- I'll be ready and waiting with my Math Midway ruler!" And Sally was excited, too: "I wonder if you could do the same thing with an ordinary 12-inch ruler?"
What do you think? What's the fewest number of marks you could put on a 12-inch ruler and still be able to measure every distance from 1 inch to 12 inches? Try to solve it, and make a table of how to measure each one of the distances. When you're done, click here to compare your solution to Sally's.
Get answers to these puzzles: