Suppose there are two bowls full of cookies.Bowl 1 has 20 chocolate chip and 30 plain cookies,while bowl 2 has 25 of each. Fred picks a bowl at random and then picks a cookie at random
i) What is the probability that Fred picks a plain cookie?
ii) If the cookie Fred picked is a plain one,what is the probability that it was from bowl 1?
Hello, Matty!
A slightly different approach . . .
Suppose there are two bowls full of cookies.
Bowl #1 has 20 chocolate chip and 30 plain cookies; Bowl #2 has 25 of each.
Fred picks a bowl at random and then picks a cookie at random.
a) What is the probability that Fred picks a plain cookie?
. . Therefore: .
bi) If the cookie Fred picked is a plain one,
what is the probability that it was from Bowl #1?
Bayes' Theorem: .
We have: .