There are 100 gumdrops. 73 of them are large, and the rest are small. 39 of them are red, and the rest are other colors. 19 of the gumdrops are large red ones. You choose 1 gumdrop at random, and it is that yummy red color. What is the probability that the gumdrop is large, given that it is red?

Question

anonymous · Answer

73 large and 27 small
39 red and 61 not red
19 both large and red

set up a table
                  large   small
                    73        27
red      39     19 
not red 61

can you fill out the rest of the table?

anonymous · Answer

And having done that what fraction of red gumdrops are large?

anonymous · Answer

is large, I guess.

anonymous · Answer

61/100 ?

anonymous · Answer

So the way you fill out the table is simple arithmetic,  Can you do that?

anonymous · Answer

You can also do this problem by P(A|B) and so on, but this is easier for a simple problem.

anonymous · Answer

large   small
                    73        27
red      39     19        20
not red 61    54          7

OK?

anonymous · Answer

I still don't fully understand

anonymous · Answer

You have 100 gumballs
some fraction red and the rest not
some fraction large and the rest small
once you know one more number
like large AND red
you know everything else there is to know

anonymous · Answer

read about it here http://telliott99.blogspot.com/2009/06/bayesian-analysis.html lots and lots of posts!