1. ## Bayes's Theorem

Hi!

Say there is a deck of 100 cards:

Red w/ numbers = 40
Red w/ figures=15
Black w/ numbers=35
Black w/ figures=10

The only information known is that 55% of the cards are red and 45% of the cards are black and 75% of the cards have numbers and 25% of the cards have figures. That is the above-referenced number of cards is not known.

How one would apply Bayes’ Theorem to calculate the probability of a card being red w/ numbers? From the information given, the answer is 40%.

Thank you!

Dr. T.

2. ## Re: Bayes's Theorem

You don't need Bayes theorem for that. There are 40 cards that are red w/ numbers out of 100 total. 40/100 is 40%.

3. ## Re: Bayes's Theorem

Originally Posted by Dason
You don't need Bayes theorem for that. There are 40 cards that are red w/ numbers out of 100 total. 40/100 is 40%.
Dason,

I was not clear. I meant to find out the probability is only the percentages but not the number of cards is known.

Dr. T.

4. ## Re: Bayes's Theorem

Maybe try rewriting your whole problem? It's not clear to me what you actually mean.

5. ## Re: Bayes's Theorem

It appears that percentages alone cannot be used to calculate the probability.

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