Question

Gina has a jar of marbles that contains 7 blue marbles, 5 red marbles, and 8 green marbles. She randomly selects a marble, records the color, and places the marble back into the jar. She then selects another marble. What is the probability that Gina randomly selected two red marbles. ( fraction in simplest form )

Answer 1

The probability that Gina randomly selected two red marbles is 1/19

Explanation:

Total number of marbles = 7 + 5 + 8

                                          = 20

The probability of getting two red marbles in the fraction form is given as:

P(first red marble) = number of red marbles / total number of marbles

P(first red marble) = $\frac{5}{20} = \frac{1}{4}$

P(second red marble) = number of red marbles after 1 white marble is removed / total number of marbles after 1 red marble is removed.

P(first red marble) = $\frac{4}{19}$

P(two red marbles) = P(first) X P(second)

                              = $\frac{1}{4} X \frac{4}{19}$

                              = $\frac{1}{19}$

Therefore, the probability that Gina randomly selected two red marbles is 1/19