Thread: probability problem

Hi there a freind posed me this question unfortunatly probability isn't my strongest area:

There area total of 75 balls of which 15 are red.

If 28 balls are selected at random what s the probability that all the red balls are chosen?

Any help would be appreciated.

Originally Posted by NeilT

Hi there a freind posed me this question unfortunatly probability isn't my strongest area:

There area total of 75 balls of which 15 are red.

If 28 balls are selected at random what s the probability that all the red balls are chosen?

Any help would be appreciated.

A good opportunity then for you to work on a weakness. Review the Hypergeometric Distibution.

thanks! i've calculated an approximate answer of 0.0156 (3 sig figs)

have to admit i'm surprised it's as small.