Math 143 C/E, Spring 2001
IPS Reading Questions
Chapter 4, Section 4

1. In Example 4.19 (p. 326) the random variable X = winnings (in dollars) from a Tri-State Pick 3 lottery ticket. The expected value (or mean) of this random variable is $0.50. Just what is meant here by the words “expected value”? Does your interpretation hold up to Example 4.20, where the random variable X = # of heads obtained from four coin tosses has an expected value of 2? Does it hold up to Example 4.21, where X = size of a household has an expected value of 2.6?

   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

2. We showed in class that the expected value (mean) of the random variable X = sum of pips on two dice is 7. With two dice of your own and enough time on your hands, how might you illustrate the law of large numbers?

   
   
   
   
   
   
   
   

3. What examples on pp. 331-332 do the IPS authors give to substantiate the claim that we are unable “to accurately distinguish random behavior from systematic influences” (this quote comes from p. 332, about half-way down the page)?

   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

4. The heights (in inches) of American men ages 18-74 are generally distributed as N(67, 3), while those of women in the same age group are N(64.5, 2.5). Let us associate the random variable X with the heights of men and Y with the heights of women, and let Z = X+Y. Would you think the distribution of Z appropriate to describe the combined heights of married couples? Why or why not?