Statistics 220E

Homework 3

Due Wednesday, January 28, 1998

1. WW 3-22 ,WW 3-24
2. WW 4-7
3. WW 4-42
4. Urn A has four red, three blue, and two green balls. Urn B has two red, three blue, and four green balls. A ball is drawn from urn A and put into urn B, and then a ball is drawn from urn B.

   (a) What is the probability that a red ball is drawn from urn B ?

   (b) If a red ball is drawn from urn B, what is the probability that a red ball was drawn from urn A ?

5. A fire insurance company has high-risk, medium-risk, and low-risk clients, who have, respectively, probabilities .02, .01, and .0025 of filing claims within a given year. The proportions of the numbers of clients in the three categories are .10, .20, and .70, respectively. What proportion of the claims filed each year come from high-risk clients ?