Your statistics teacher tells you that there is a 50% chance that a coin will land heads up. How would you state this chance in terms of a probability?

1 Answer
Jan 14, 2015

0.5 or 12

IF we have a fair coin there are two possibilities:
heads or tails

Both have an equal chance.

So you divide the favourable chances ("success") S by the total number of chances T:

ST=12=0.5=50%

Another example:
What is the chance of rolling less than three with a normal die?
S ("success") = (1 or 2) = 2 possibilities
T (total) = 6 possibilities, all equally probable
Chance ST=26=13

Extra:
Almost no real-life coin is completely fair.
Depending on the faces of the heads and tail, the centre of gravity may be a tiny bit on the heads or tail side.
This will only show on long term mega-flipping, but this has been done! Google!