Respuesta :
Answer:
a) There is a 60% probability that he picks up a blue pen and recognizes it as blue.
b) There is a 62.5% probability that he chooses a pen and thinks it is blue.
c) Given that he thinks he chose a blue pen, there is a 96% probability that he actually chose a blue pen.
Step-by-step explanation:
We have these following probabilities
A 75% probability that a pen is blue
A 25% probability that a pen is green
If a pen is blue, an 80% probability that the boy thinks it is a blue pen
If a pen is blue, a 20% probability that the boy thinks it is a green pen.
If a pen is green, a 90% probability that the boy thinks it is a green pen.
If a pen is green, a 10% probability that that the boy thinks it is a blue pen.
a) What is the probability that he picks up a blue pen and recognizes it as blue?
There is a 75% probability that he picks up a blue pen.
There is a 80% that he recognizes a blue pen as blue.
So
[tex]P = 0.75*0.8 = 0.6[/tex]
There is a 60% probability that he picks up a blue pen and recognizes it as blue.
b) What is the probability that he chooses a pen and thinks it is blue?
There is a 75% probability that he picks up a blue pen.
There is a 80% that he recognizes a blue pen as blue.
There is a 25% probability that he picks up a green pen
There is a 10% probability that he thinks a green pen is blue.
So
[tex]P = 0.75*0.80 + 0.25*0.10 = 0.625[/tex]
There is a 62.5% probability that he chooses a pen and thinks it is blue.
c) (Given that he thinks he chose a blue pen, what is the probability that he actually chose a blue pen?
There is a 62.5% probability that he thinks that he choose a blue pen.
There is a 60% probability that he chooses a blue pen and think that it is blue.
So
[tex]P = \frac{0.6}{0.625} = 0.96[/tex]
Given that he thinks he chose a blue pen, there is a 96% probability that he actually chose a blue pen.
