The scores on an examination are normally distributed with mean p = 70 and standard deviation a = 8. Suppose that the instructor decides to assign letter grades according to the following scheme (left endpoint included). Scores Grade Less than 58...................... F 58 to 66........................... D 66 to 74........................... C 74 to 82........................... B 82 and above..................... A Find the percentage of students in each grade category.
Added by Javier M.
Step 1
For F grade: z = (58 - 70) / 8 = -1.5 For D grade: z = (66 - 70) / 8 = -0.5 For C grade: z = (74 - 70) / 8 = 0.5 For B grade: z = (82 - 70) / 8 = 1.5 For A grade: z = (100 - 70) / 8 = 3.75 (we use 100 as an approximation of infinity) Show more…
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