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Recall from Example 1 that whenever Suzan sees a bag of marbles, she grabs a han

ID: 3036963 • Letter: R

Question

Recall from Example 1 that whenever Suzan sees a bag of marbles, she grabs a handful at random. She has seen a bag containing four red marbles, three green ones, four white ones, and one purple one. She grabs five of them. Find the probability of the following event, expressing it as a fraction in lowest terms. She has two green ones and one of each of the other colors. Recall from Example 1 that whenever Suzan sees a bag of marbles, she grabs a handful at random. She has seen a bag containing three red marbles, two green ones, four white ones, and two purple ones. She grabs seven of them. Find the probability of the following event, expressing it as a fraction in lowest terms. She does not have all the red ones.

Explanation / Answer

11) total marbles = 4 + 3 + 4 + 1 = 12

She grabs 5 marbles

P(2 greens and 1 of each of others) = 3C2 * 4C1 * 4C1 * 1C1 / 12C5

                                                          = 3 * 4 * 4 * 1 / 792

                                                          = 2/33

12) total marbles = 3 + 2 + 4 + 2 = 11

She grabs 7 marbles

P(not all reds) = 1 - P(all reds)

                       = 1 - (3C3 * 8C4 / 11C7)

                       = 1 - (1 * 70 / 330)

                       = 260/330

                       = 26/33