A statistics instructor has decided to grade on a curve that results in the foll
ID: 3131489 • Letter: A
Question
A statistics instructor has decided to grade on a curve that results in the following distribution: A’s – top 10% of students; B’s – next 20% of students; C’s – middle 40% of students ; D’s – next 20% of students; F’s – bottom 10% of students . If the exam has a mean grade of 75 with a standard deviation of 15, what exam scores would border each letter grade (provide answers to the nearest integer)?
A's would be students with scores above ____
B's would be grades above ____ and up to ____
C's would be grades above ____ and up to ____
D's would be grades above ____ and up to ____
F's would be grades at or below ____
What exam scores would border each letter grade if the exam had a mean of 80 with a standard deviation of 5 (provide answers to the nearest integer)?
A's would be students with scores above ____
B's would be grades above ____ and up to ____
C's would be grades above ____ and up to ____
D's would be grades above ____ and up to ____
F's would be grades at or below ____
Is grading on a curve always a benefit to every student? Who do you think it benefits and when? How would you feel with a grade of 72, 82, and 92 in each case? (This input box will not be automatically graded, but will be reviewed by the instructor.)
A statistics instructor has decided to grade on a curve that results in the following distribution: A’s – top 10% of students; B’s – next 20% of students; C’s – middle 40% of students ; D’s – next 20% of students; F’s – bottom 10% of students . If the exam has a mean grade of 75 with a standard deviation of 15, what exam scores would border each letter grade (provide answers to the nearest integer)?
A's would be students with scores above ____
B's would be grades above ____ and up to ____
C's would be grades above ____ and up to ____
D's would be grades above ____ and up to ____
F's would be grades at or below ____
What exam scores would border each letter grade if the exam had a mean of 80 with a standard deviation of 5 (provide answers to the nearest integer)?
A's would be students with scores above ____
B's would be grades above ____ and up to ____
C's would be grades above ____ and up to ____
D's would be grades above ____ and up to ____
F's would be grades at or below ____
Is grading on a curve always a benefit to every student? Who do you think it benefits and when? How would you feel with a grade of 72, 82, and 92 in each case? (This input box will not be automatically graded, but will be reviewed by the instructor.)
Explanation / Answer
A statistics instructor has decided to grade on a curve that results in the following distribution: A’s – top 10% of students; B’s – next 20% of students; C’s – middle 40% of students ; D’s – next 20% of students; F’s – bottom 10% of students . If the exam has a mean grade of 75 with a standard deviation of 15, what exam scores would border each letter grade (provide answers to the nearest integer)?
FOR A:
First, we get the z score from the given left tailed area. As
Left tailed area = 1 - 0.10 = 0.9
Then, using table or technology,
z = 1.281551566
As x = u + z * s,
where
u = mean = 75
z = the critical z score = 1.281551566
s = standard deviation = 15
Then
x = critical value = 94
A's would be students with scores above 94. [ANSWER]
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FOR B:
It is from 70th to 90 percentiles.
First, we get the z score from the given left tailed area. As
Left tailed area = 0.7
Then, using table or technology,
z = 0.524400513
As x = u + z * s,
where
u = mean = 75
z = the critical z score = 0.524400513
s = standard deviation = 15
Then
x = critical value = 82.86600769
B's would be grades above 83 and up to 93. [ANSWER]
***************
FOR C:
It is from 30th to 70th percentile:
First, we get the z score from the given left tailed area. As
Left tailed area = 0.3
Then, using table or technology,
z = -0.524400513
As x = u + z * s,
where
u = mean = 75
z = the critical z score = -0.524400513
s = standard deviation = 15
Then
x = critical value = 67.13399231 = 67
Hence, between 67 and 82. [ANSWER]
******************
FOR D:
It is from 10th to 30th percentile:
First, we get the z score from the given left tailed area. As
Left tailed area = 0.1
Then, using table or technology,
z = -1.281551566
As x = u + z * s,
where
u = mean = 75
z = the critical z score = -1.281551566
s = standard deviation = 15
Then
x = critical value = 55.77672652 = 56
Hence, from 56 to 66. [ANSWER]
************************
FOR F:
Hence, F's would be grades at or below 55. [ANSWER]
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