Question 9 of 10, Step 1 of 1 Correct An English professor assigns letter grades

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Question 9 of 10, Step 1 of 1 Correct An English professor assigns letter grades on a test according to the following scheme. A: Top 15% of scores B: Scores below the top 15% and above the bottom 64% C: Scores below the top 36% and above the bottom 2 1% D: Scores below the top 79% and above the bottom 8% F: Bottom 8% of scores Scores on the test are normally distributed with a mean of 76.5 and a standard deviation of 8.4. Find the numerical limits for a D grade. Round your answers to the nearest whole number, if necessary Answer TablesKeypad and Standard Normal Table 0 to z Submit Answer 7 Hawkes Learning rfbere t search

Explanation / Answer

Normal distribution params are:

Mean = 76.5

Stdev = 8.4

For a D grade it should be ? between below top 79% and above the bottom 8%:

Therefore, the area of .79 to .92 is the area with Z values of -.8064 and -1.4051, respectively

The scores are Mean + Z*Stdev = 76.5 +8.4*(-1.4051) to 76.5 +8.4*(-.8064)

= 64.6972 to 69.7262

To get a D grade we have to get a score 64.6972 to 69.7262 or 65 to 69

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