5.85 Working on summer vacation. In Exercise 4.68 (p. 212), you learned that 35% of U.S. adults do not work at all while on summer vacation (Adweek/Harris July 2011 poll). Now con- sider a random sample of 1,000 U.S. adults and let x repre- sent the number who do not work during summer vacation. a. What is the expected value of x? Interpret this value practically. b. Find the variance of x. c. Find the approximate probability that x is less than 325 d d. Would you expect to observe 390 or more U.S. adults in the sample of 1,000 who do not work during summer vacation? Explain. Exercise 4 70