The following is a partial list of grades for students in Dr you just created, f
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The following is a partial list of grades for students in Dr you just created, find the new curved letter grades that given their raw scores n Dr. Smith's the stud 5. Biology Exam Grades Raw Score / Grade 821B 77/? 91 /A 86/8 75/C 66/D 88rB 69/0 79/C Tray Sharon Eric Grading Curve Option II After reviewing the results, Dr. Smith decides to consider an alternate to assign exam grades as follows. A: Students whose scores are at least two standard deviations above the B:Students whose scores are from one up to two standard deviat to consider an alternate curving method. Hle deside mean of the standardized above the mean of the test. standardized test up to C: Students whose scores are from one standard deviation below the mean ooc standard deviation above the mean of the standardized test D Stdents whos scores are trom two standard deviations below the mean up to ane s F:Students whose scores are more than two standard deviations below the mean of the are from two standard deviations below the mean up to one standard deviation below the mean of the standardized test. standardized test. 6. Using the previous information, create Dr. Smith's new grading scale. (Round to the nearest whole number.) A: B: C: D. F: 0 100 7. Using the grading scale you just created, return to the partial list ot eit raw scs scores curved letter grades that the students will receive on their tests given 8. Review the grades each student you fel is fairer? Explain why received using the two grading scales. Whichgrading sale do theExplanation / Answer
Mean score = 78
Standard deviation = 8
4. Find the exam scores corresponding to the curved grading scale.
Percentile can be converted into a probability by dividing the percentile with 100. We know the scores follow normal distribution. So we have used EXCEL function
NORM.INV(probability, mean, standard deviation)
to calculate score respective to each upper and lower limit of the curved grading method
For example. The lower limit for grade A, 90th Percentile which will be an equal probability of 0.9. Inserting the values in the excel function we get
Norm.inv(0.9,78,8) = 88.25241 which can be rounded to whole number 88. The final table of scores look like following
A: 88-100
B:85-88
C:82:84
D:80-82
F:0-80
5) Since due to rounding to nearest whole number some of the scores are shared between two grades which will make scoring difficult. Thus, I have small change, if upper grade (like A) includes 88, grade B will exclude. Thus the need rounded graded looks like following:
A: 88-100
B:85-87
C:82:84
D:80-81
F:0-79
Using the above grading of scores the new grades assigned to students are as follows:
Grading Curve option II
Let X be the test scores and s stands for standard deviation
A: X > mean + 2s
B:mean + 1s < X <= mean + 2s
C:mean - 1s < X <= mean + 1s
D: mean - 2s < X <= mean - 1s
F: X<= mean - 2s
Using this new grading curve, the upper and lower limit will be inserting the values of mean and standard deviating in the limit listed above. we get
A: (94,100]
B:(86,94]
C:(70,86]
D:(62,70]
F:[0,62]
7. Students score on the basis of option II grading curve
8. Option II grading curve is fairer as compared to former grading scheme on percentiles because the grading was too skewed in the former for grades B, C, and D. However for option II, grades are almost equally divided for middle grades of B,C, and D. Due to skewed scores in grades, most of the students received F grade in the former system.
GRADE Upper limit probability Scores Rounded scores Lower Limit probability Scores Rounded scores A 100 1 100 100 90 0.9 88.25241 88 B 89 0.89 87.812225 88 80 0.8 84.73297 85 C 79 0.79 84.45137 84 70 0.7 82.1952 82 D 69 0.69 81.9668028 82 60 0.6 80.02678 80 F 59 0.59 79.8203598 80 0 0 0 0Related Questions
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