Making unfair coins

Can you make a coin that falls, on average, heads more often than tails?

• Is it possible?
• How easy will it be to try
• What bias do you expect you can achieve

I'll leave you to think of a way of adapting an existing coin or making one from scratch. I expect you can be put in the Tower of London and boiled in oil for defacing coins of the realm so don't try to bribe a policeman with one of your creations.

Now we come to the interesting bit. How are you going to test it? Ah yes. I hadn't thought of that. Do you make a machine? In any event does the way you toss the coin affect the result? Ok I relent:- Try a good one side by side with your special.

Being of a scientific turn of mind you think through your experiment first.

What amount of bias do you think you can achieve?

• Technically by optimising your design
• Practically, before someone notices!

How many tosses are you likely to need before you can be sure of the trend?

During your experiments you may find you have a knack of throwing that has a bias with a good coin.

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