Ngahina is playing a game. She counts how many times in a row she has to toss a coin until it comes up heads. She says that she will never have to toss it more than four times.
Is she right? How likely is it that she would toss a coin four times and get tails every time?
Solution:
For any one turn it is very unlikely that she will toss the coin four times without getting heads, but if she keeps on playing the game she will eventually have a turn when she gets tails four times in a row.
If she tosses the coin once the chance of not getting heads is 1/2.
If she tosses the coin twice the chance of not getting heads is 1/4.
If she tosses the coin three times the chance of not getting heads is 1/8.
If she tosses the coin four times the chance of not getting heads is 1/16.