Recall from Example 1 that whenever Suzan sees a bag of marb

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, five 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 has at least one green one.

Solution

Probability of getting at least one green marbles= probability of one green marble + probability of 2 green marbles

probability of 1 green marble= 2C1*10C6/12C7=2* 210/ 792=420/792

probability of 2 green marbles= 2C2*10C5/12C7=1*252/792

Therefore required probability= 420/792 + 252/792= 672/792=28/33