Question

Probability--

There are two boxes...the first box has 3 black balls and 1 blue ball in it.

The second box has 6 black balls and 2 in blue balls in it.

a. Which of the following two boxes would you choose if you were picking 1 ball and wanted black? Justify your answer.

b. Then what if you were picking 2 balls (without replacement) and wanted 2 black ones?

Answer 1

prob of getting one black from 1st box
= 3/4
prob of getting one black from 2nd box
= 6/8 = 3/4

mmmmmhhhh?

prob(2 blacks from 1st) = (3/4)(2/3) = 1/2
prob(2 blacks from 2nd) = (6/8)(5/7) = 15/28

mmmh again!