Ricardo's old toaster can hold at most two slices of bread and toast them on one side at a time. He wants his bread toasted on both sides and buttered on one side.
- 3 seconds to put each slice into the toaster and,
- 30 seconds to toast one side of 1 or 2 slices and,
- 3 seconds to reverse a slice and,
- 12 seconds to butter one side (that side must already be toasted).
- 3 seconds to remove a slice from the toaster without putting it back in reverse.
Assuming that, only one of these
operations can be done at a time:
In how short a time can Ricardo toast and butter three slices?
I know that this is against the rules, but I am going to butter my first side while the last two slices are toasting. Otherwise, I'm just twiddling my thumbs and watching the toast burn ...