Originally Posted by

**PatCal** I am trying to help my child with her homework, and I don't have a clue how to answer this.

Four ball are randomly selected without replacement from an urn containing 20 balls numbered 1 - 20

1.A) Let Y denote the number of balls numbered 16 or higher. Determine the probabilty distribution ( probability mass function) of Y.

1.B) Use the probabilty mass function to determine the probability that the largest value in the selection is at most 15.

2.A) Let X equal the largest number in the selection. Is X hypergeometric?

2.B) Determine the probablity distribution (probability mass function) of X. Use this to determine the probability that the largest value is at most 15.

I could use any help you can offer on this. Thanks.