Suppose a jar contains 12 red marbles and 32 blue marbles If

Suppose a jar contains 12 red marbles and 32 blue marbles. If you reach in the jar and pull out 2 marbles at random, find the probability that both are red.

Solution

32+12=44 marbles in total.

At our first pull, there is an 12/44 chance that a red will be pulled--the number of red out of the total number.

At the second pull there is a 11/43 chance that the second marble will be red as well--how many red/total are still in there.

From here, we multiply our two fractions together:

12/44*11/43=0.27*0.26=0.06907

When we divide, we get about 0.06907, which rounds to 6.90%, depending if you want to keep it in fraction, ratio, or percentage form.