Mathematics Homework Help

Suppose you sample an urn with 12 red balls and 6 green balls. You choose three balls without replacement. 

A.) What is the probability of choosing exactly 2 red balls? 

B.) What is the probability of choosing at least 2 red balls? 

c.) What is the probability you draw one red ball and two green balls? 

D.) What is the probability mass function for the number of red balls drawn? What is the mean and the standard deviation for this distribution?