PROBABILITY help

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PerMortenIvar

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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 plantet, 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?


 
PerMortenIvar said:
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 plantet, 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?
Click to expand...
I'm guessing as to what that really means.

a) \(\displaystyle \left[(P_a)^2+(P_b)^2\right](0.5)\) is the probability that both seeds will germinate if two of the same are planted.

b) Apply the conditional probability formula.
 
pka said:
I'm guessing as to what that really means.

a) \(\displaystyle \left[(P_a)^2+(P_b)^2\right](0.5)\) is the probability that both seeds will germinate if two of the same are planted.

b) Apply the conditional probability formula.
Click to expand...

I am having problems with b). I find that the probability for both seeds to germinate: P = Pa^2 + 2PaPb + Pb^2 that i will use in the conditional probability formula. The problem is that the text say that i should find probability if i let Pa = 0.9 and Pb = 0.2, which gives that the total probability for both seeds to germinate will be larger than 1.
 
PerMortenIvar said:
I am having problems with b). I find that the probability for both seeds to germinate: P = Pa^2 + 2PaPb + Pb^2 that i will use in the conditional probability formula. The problem is that the text say that i should find probability if i let Pa = 0.9 and Pb = 0.2, which gives that the total probability for both seeds to germinate will be larger than 1.
Click to expand...
Given the above, I have no idea that the "H***" is going on.
From the OP, I assumed that someone planted two seed of the same type determined by a coin toss.
If that is correct, then how can there be a planting of two different types of seeds?
On the other hand, I the question mean that two seeds of the same type are planted then your view is mistaken.
 
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