# Nine minute fuse

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Here is a puzzle I came up with after getting the wrong solution to one of Richard Wiseman's Friday puzzles.

## Puzzle

You have all but finished setting up your very well timed fireworks display. All you have left is one kamuro shell for which you need to set a nine minute fuse. Unfortunately, all you have left are a few seven minute fuses and a few four minute fuses. Due to shoddy construction, these fuses do not burn at a constant rate - in fact, even two fuses of the same type might burn at different rates over different parts of the fuse. Is it possible to connect some fuses together (using a fuse glue which does not change burning time, of course) to get a fuse which will burn in exactly nine minutes? If so, how?

## Variation

After completing your work, you find a super finally type firework that you want to use. Using only the four and seven minute fuses you have left, can you make a fuse that will burn for exactly nine and a half minutes? If so, how?