Bunuel wrote:

Jenny's cabinet contains 4 bags of tortilla chips, 4 bags of potato chips, and 5 bags of popcorn. Jenny reaches into the cabinet and draws a bag at random, places it on the counter, and returns to draw one more bag at random. What is the probability that she pulls out two bags of popcorn?

A. 1/13

B. 5/39

C. 2/13

D. 3/13

E. 10/39

As there is an explicit rule for calculating the probability of multiple independent experiments (in this case, taking bags from the cabinet), we'll use it.

This is a Precise approach.

The probability that the first bag is a popcorn bag is 5/(4+4+5) = 5/13.

As there are now 12 bags left, 4 of which contain popcorn, the probability of drawing another bag of popcorn is 4/12 = 1/3

So, the probability of drawing 2 bags of popcorn is (5/13)*(1/3) = 5/39.

(B) is our answer.

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