2 Probability Problems

[Guest]

Let the germination probability (the probability that a seed sprouts) for seed A be Pa and B be Pb.


a) You plant two seeds of the same kind. If you turn heads or tails of what sort you planted, what is the probability that 2 seeds germinate?
b) A student plant 2 seeds, but he had forgotten to note what sort of seed he had planted. What is the probability that it was A if both germinate?

[Guest]

A student plant 2 seeds, but he had forgotten to note what sort of seed he had planted. What is the probability that it was A if both germinate?

The chance is 1/2 or 50% because he has 2 plants and 1 of them is A.

[Guest]

I think you need to use Bayes' rule to solve both problems.