Who is asking: Student
I have a brain teaser. My name is Amanda, and I am a student in the middle level category. Here's the question:
You have invited 11 people over to your house one day, and your friends are hungry. You go into the kitchen and find out you only have 1 donut (with a hole in the middle). In order to feed 12 people (including you), you must cut the donut into 12 pieces with only using a straight knife and cutting 3 times. This is NOT a trick question.
I can help, provided that the pieces need not be of equal size.
It would not be possible to cut a muffin into 12 pieces with 3 straight cuts: The first cut would produce two pieces. Stacking these on top of each other (or in a line), it would be possible to split each of these in two with the second cut, resulting in 4 pieces. then putting all of these in a line and cutting through all of these with the last cut would result in 8 pieces, which is less than 12.
With a donut, the problem is resolved as follows: Cutting
the O-shaped donut results in two C-shaped halves.
You stack these one atop the other and cut a straight line through the C shape to split each C shape into THREE pieces.
This gives you 6 donut pieces (though they may not all have the same weight). You then line these up on the table and cut horizontally through them all, and you get 12 pieces. Cheers,