794 CHAPTER 12 Statistics 45. A Grade of B A mean average of 80 or greater for five exams is needed for a final grade of B in a course. Jorge’s first four exam grades are 73, 69, 85, and 80. What grade does Jorge need on the fifth exam to get a B in the course? 93 or greater 46. Grade of A A mean average of 90 or greater for 6 exams is needed for a final grade of A in a course. Sandy’s first five exam grades are 92, 90, 87, 93, and 96. What grade does Sandy need on the sixth exam to get an A in the course? 82 or greater 47. Grading Methods A mean average of 60 or greater on seven exams is needed to pass a course. On her first six exams, Sheryl received grades of 52, 72, 80, 65, 57, and 69. a) What grade must she receive on her last exam to pass the course? 25 or greater b) An average of 70 is needed to get a C in the course. Is it possible for Sheryl to get a C? If so, what grade must she receive on the seventh exam? Yes; 95 or greater c) If her lowest grade of the exams already taken is to be dropped, what grade must she receive on her last exam to pass the course? 17 or greater d) If her lowest grade of the exams already taken is to be dropped, what grade must she receive on her last exam to get a C in the course? 77 or greater 48. Grading Methods A mean average of 70 or greater on six exams is needed to get a C in a course. On his first 5 exams, Quincy received grades of 74, 82, 76, 70, and 54. a) What grade must he receive on his last exam to get a C? 64 or greater b) A mean average of 80 is needed to get a B in the course. Is it possible for Quincy to get a B? If so, what grade must he receive on the sixth exam? No, he would need a grade of 124 or greater. c) If the lowest grade of the exams already taken is to be dropped, what grade must he receive on his last exam to get a C in the course? 48 or greater d) If the lowest grade of the exams already taken is to be dropped, would it be possible for Quincy to get a B? If so, what grade would he need to receive on his last exam? Yes. He would need a 98 or greater. 49. Grocery Expenses The Taylors have recorded their weekly grocery expenses for the past 12 weeks and determined that the mean weekly expense was $85.20. Later they discovered that 1 week’s expense of $74 was incorrectly recorded as $47. What is the correct mean? $87.45 50. Entertainment Expenses The Comstocks have recorded their monthly entertainment expenses for the past 6 months and determined that the mean monthly expense was $250. Later, they discovered that one month’s expense of $175 was incorrectly recorded as $157. What is the correct mean? $253 51. Quartiles The prices of the 19 top-rated All-In-One Black and White Laser Printers, as reported in the July 2023 issue of Consumer Reports, are as follows: $140 $150 $160 $170 $200 $200 $210 $210 $220 $230 $235 $250 $250 $250 $280 $280 $300 $300 $330 Determine a) Q2 $230 b) Q1 $200 c) Q3 $280 52. Quartiles The prices of the 19 top-rated smart speakers, as reported in the May/June 2023 issue of Consumer Reports, are as follows: $40 $75 $80 $100 $170 $175 $200 $200 $220 $230 $250 $250 $280 $290 $300 $380 $400 $400 $800 Determine a) Q2 $230 b) Q1 $170 c) Q3 $300 53. Quartiles The prices of the 20 top-rated noise-canceling wireless headphones, as reported in the May/June 2023 issue of Consumer Reports, are as follows: $330 $550 $400 $300 $500 $280 $350 $400 $250 $350 $45 $60 $250 $200 $300 $170 $300 $150 $80 $100 Determine a) Q2 $290 b) Q1 $160 c) Q3 $350 54. Quartiles The prices of the 20 top-rated sunscreens, as reported in the July 2023 issue of Consumer Reports, are as follows: $9.00 $17.50 $3.80 $7.30 $4.80 $11.00 $4.80 $5.00 $10.00 $7.00 $24.00 $19.00 $18.00 $15.70 $12.00 $11.00 $6.00 $11.00 $14.50 $10.00 Determine a) Q2 $10.50 b) Q1 $6.50 c) Q3 $15.10 55. College Admissions Jonathan took an admission test for the University of California and scored in the 85th percentile. The following year, Jonathan’s sister Kendra took a similar admission test for the University of California and scored in the 90th percentile. a) Is it possible to determine which of the two answered the higher percent of questions correctly on their respective exams? No b) Is it possible to determine which of the two was in a better relative position with regard to their respective populations? Explain. Yes, Kendra was in better relative position. $ $ $ $ $ $
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