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Birthday Cake

Math brain teasers require computations to solve.


Puzzle ID:#662
Fun:*** (2.42)
Difficulty:** (1.57)
Submitted By:vikass***
Corrected By:MarcM1098




Suppose you are given a birthday cake which is round in shape (like a perfect circle) and you are asked to make eight equal pieces out of it by using a knife only three times. How would you proceed?

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Jul 04, 2001

Although they are the same size, they aren`t really equal because 4 are from the top and 4 are from the bottom. You could cut the cake twice as the answer states, but then move the pieces so they are all in a line and make one final long cut splitting all 4 pieces into 8 completely equal pieces. eh?
May 07, 2002

You know, I exhaust most teaser books i know of, go searching for new ones, and run into ones i've already seen.
Jan 11, 2004

Half of the little kids would be ticked to not get any icing as well! And if you saw this one before, Mogmatt, you could have submitted it first and not have had to complain.
Jul 14, 2004

For the 3rd cut, you could also put the quarter pieces on top of each other and cut straight down.
May 26, 2006

this shud b in trick not maths
May 26, 2006

this shud b in trick not maths
Jun 16, 2006

I agree with canu. Then all the little kids would get icving too.
Aug 05, 2006

I don't think a piece of cake is worth that. Who would limit you to only 3 cuts?
Aug 16, 2007

Cute, but then the peices are smaller. I call a bottom piece!
Sep 27, 2007

I don't understand the way that the answer is worded at all -- did they mean that after the first two cuts are made the pieces are stacked on top of each other or in a line and **then** the final cut is made? Because otherwise, if the four pieces are left as they are, it is impossible to just make one more cut and end up with eight equal pieces.

Jan 29, 2009

My solution was to cut an inner circle with a radius of 1/sqrt(2) times the cake radius and then cut two diagonals. At least everyone gets some of the top icing that way.
Mar 28, 2009

To heck with the problems, I just Love Java's solutions - Way to go!

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