Quote:
Originally Posted by pkdk
I am sorry your maths is poor. If I only have ten cards how can you have something out of 52?
it would be out of ten.
The total number of cards doesn't have to match the denominator in the probability fraction. You can make the denominator any number as long as you adjust the numerator accordingly. People tend to set the numerator at 1 and then adjust the denominator accordingly to make it easier to visualize.
But if you want the denominator to match the total number of cards, then in that situation it is (rounded): 0.192/10 or written as a percentage, roughly a 1.92% chance.
Consider weather forecasts:
It can either rain or not rain. That is 2 items or events. Say there is a 20% chance of rain. If that were to be written as a fraction it could be written 1/5. There are only 2 items or events, but the denominator is not a 2. It doesn't need to be. If you wanted the denominator to be a 2, then you could write it that way and it would be 0.4/2. 0.4/2 is still 20%; the same as 1/5. We could also write it 12/60 if we felt like it for some reason or 117/585 or 0.05/0.25.
I think in the world you would more often see 1/5 written than 0.4/2 (or any of the other examples above) to notate a 20% chance. I think most people find it easier to visualize and immediately have a good understanding of a 1/5 chance than a 0.4/2 chance, so they use the 1/5.
Last edited by Lego05; 02-28-2018 at 10:32 PM.