182 CHAPTER 3 Probability 27. A random sample of 250 working adults found that 74% access the Internet at work, 88% access the Internet at home, and 72% access the Internet at both work and home. Find the probability that a person in this sample selected at random accesses the Internet at home or at work. 28. A sample of 6500 automobiles found that 1560 of the automobiles were black, 3120 of the automobiles were sedans, and 1170 of the automobiles were black sedans. Find the probability that a randomly chosen automobile from this sample is black or a sedan. In Exercises 29–32, find the probability. 29. A card is randomly selected from a standard deck of 52 playing cards. Find the probability that the card is between 4 and 8, inclusive, or is a club. 30. A card is randomly selected from a standard deck of 52 playing cards. Find the probability that the card is red or a queen. 31. A 12-sided die, numbered 1 to 12, is rolled. Find the probability that the roll results in an odd number or a number less than 4. 32. The spinner shown at the left is spun. The spinner is equally likely to land on each number. Find the probability that the spinner lands on a multiple of 3 or a number greater than 5. In Exercises 33 and 34, use the pie chart at the left, which shows the percent distribution of the number of students in U.S. public schools in a recent year. (Source: U.S. National Center for Education Statistics) 33. Find the probability of randomly selecting a school with fewer than 500 students. 34. Find the probability of randomly selecting a school with 300 or more students. In Exercises 35–38, the bar graph shows the results of a survey in which 8806 undergraduate students were asked how many hours they spend on studying and other academic activities outside of class in a typical week. (Source: American College Health Association) Number responding Time (in hours) Weekly Study Time of Undergraduates 1654 2452 1810 1309 714 0–5 6–10 11–15 16–20 21–25 25+ 867 500 1000 1500 2000 2500 35. Find the probability of randomly selecting an undergraduate who studies more than 20 hours per week. 36. Find the probability of randomly selecting an undergraduate who studies less than 11 hours per week. 37. Find the probability of randomly selecting an undergraduate who does not study from 6 to 10 hours per week. 38. Find the probability of randomly selecting an undergraduate who does not study more than 15 hours per week. 1000 or more 9.4% Students in Public Schools Fewer than 300 29.8% 300–499 28.1% 500–999 32.7% FIGURE FOR EXERCISES 33 AND 34 4 6 8 2 5 3 1 7 FIGURE FOR EXERCISE 32
RkJQdWJsaXNoZXIy NjM5ODQ=