Question

3. Your economics professor is analyzing exam grades to determine whether her exams are too hard are too ha or too easy. The stem-and-leaf plot below was made of the final exam grades of students in all of her courses. Answer the following questions about the data. the folowing questonya s made of the final exam Stem-and-leaf plot: 7779 12234566777889 00111122223333344455555555566778888888899 0000001111222234444444444445566777778888999 00011123355699 0129 a. Create a box plot from the data and draw a line at the median grade. What is the median grade? b. At your university, grades in the 90s get an A, those in the 80s get a B, those in the 70s get a C, those in the 60s get a D, and those below 60 get an F. What is the mean and mode of the data set? What letter grades do they represent? c. If your economics professor is aiming for a B average, are her final exams too difficult? How do you know?

Answer 1

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63,63,63,63,63,rep (65,9),66,66,67,67,r R Script ,73.996,74.009,74.014,74.010,74.013) 47,47,47,49,51,52,52,53,54,55,56,56,57,57,57,58,58,59,61,61,66,62,62,62,63,63,63,63,63,rep(65,9),66,66,67.67.rep(6 9,79,80,80,80,81,81,81,82,83,83,85, 8,8),69,69,rep(70,6),rep(71,4),rep(72,4),73,rep(74,12),75,75,76,76,rep(77,5), rep(78,4),79,7 85,86,89,89,90,91,92,99) boxplot(x) > nedian(x) [1] 70 nean(x) [11 69.83478