A bag contains 10 red marbles and 20 white marbles. You draw a marble, keep it, and draw another. What is the probability of drawing two red marbles?
10/30*9/29
3/29
To find the probability of drawing two red marbles, we need to consider the number of favorable outcomes (drawing two red marbles) and the total number of possible outcomes (drawing any two marbles).
First, let's calculate the number of favorable outcomes. In this case, we want to draw two red marbles from the bag. Since there are 10 red marbles in the bag, the probability of drawing the first red marble is 10/30 (10 red marbles out of a total of 30 marbles).
After drawing the first red marble, the bag will contain 9 red marbles and 29 marbles in total. So, the probability of drawing a second red marble is now 9/29.
To find the probability of drawing both red marbles, we multiply the probabilities of drawing each red marble together:
P(drawing two red marbles) = (10/30) * (9/29)
Simplifying this expression, we get:
P(drawing two red marbles) = 3/30 * 9/29
P(drawing two red marbles) = 27/870
Therefore, the probability of drawing two red marbles from the bag is 27/870 or approximately 0.031 (rounded to three decimal places).
3/29
first red --> 10/30
second red --> 9/29
prob of 2 red = (10/30)(9/29) = 3/29