A jar contains seven blue marbles and six red marbles. Suppose you choose a marble at random, and do not replace it. Then you choose a second marble. Find the probability of the following event.
Both of the selected marbles are red.
The probability of selecting a red marble on the first draw is 6/13, since there are 6 red marbles out of a total of 13 marbles.
After selecting a red marble on the first draw, there are now 5 red marbles left and 12 total marbles remaining.
Therefore, the probability of selecting a second red marble is 5/12.
To find the probability of both events happening together, we multiply the probabilities:
(6/13) * (5/12) = 30/156 = 5/26
Therefore, the probability of selecting two red marbles in a row is 5/26.