15. Give everyone in the salary example a 10% raise. What’s the new average salary?
Everyone working at Bob’s diner makes $8/hour.
16. What is the expected salary per hour?
17. What is the variance of the salaries at Bob’s diner?
Let X = price of stocks in Bob’s portfolio; let Y = price of stocks in Sue’s portfolio.
Mean of X = $20, SD = $5; Mean of Y = $30, SD = $6
18. Suppose all the stocks in Bob’s portfolio double in price.
a. What happens to the mean of Bob’s stocks?
b. What happens to the variance?
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View Full Document19. Suppose all of Sue’s stocks each increase $10.00 in price.
ab.
What happens to the mean and variance of her stock prices?
20. Assume Bob and Sue’s stocks are independent.
a. What is the mean and standard deviation of their combined stock prices?
b. What is the mean and standard deviation of the difference in their stock prices?
21. Assume Bob and Sue’s stocks have correlation 0.4.
a. What is the mean and standard deviation of their combined stock prices?
b. What is the mean and standard deviation of the difference in their stock prices?
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 Fall '11
 Johnson
 Statistics, Standard Deviation, Probability distribution, Probability theory, new average salary

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