Fun With Very Small Change

Everyone knows that the probability of getting heads when you flip a coin is 1/2.  But what happens if you randomize the coin in another way?  Chance students took on that question recently.

In the first experiment, we stood pennies on edge (not a simple feat, that) and then smacked the table, recording how they fell.  In the second experiment, we spun coins on a tabletop and recorded the proportions of heads and tails. 

.

And our results are...

What this all means: The probability of a coin landing heads when the table is pounded is more than 50%.  When the coin is spun, the probability of heads is somewhat less than 1/2.  This has to do with how the coin is shaped in cross-section.

Return to the Chance home page.

Last modification: 31 August 02009.
This page is Y10K compliant.