Answer:
Kindly check explanation
Step-by-step explanation:
Given that :
Mean (m) = 72
Standard deviation (sd) = 10
Grading cutoff policy:
bottom 5% receive F
next 15% receive D
next 35% receive C
next 30% receive B
A) Give the cutoffs for the grades in this course in terms of standardized scores.
Standardized score for grade cutoff:
Locating the Zscore for the proportions on the z table :
Bottom 5% = 0.05 ; corresponding Zscore = - 1.645
next 15% receive D = (5 +15)% 0.20 ; corresponding Zscore = - 0.84
next 35% receive C = (20+35)% = 0.55 ; corresponding Zscore = 0.13
next 30% receive B = (55 + 30)% = 0.85 ; Corresponding Zscore = 1.04
B) Give the cutoffs in terms of actual total scores.
Recall:
Zscore = (x - m) /sd ; where x = actual score
x = sd*z + m
For F:
10*(-1.645) + 72 = 55.55
For D:
10*(-0.84) + 72 = 63.6
For C:
10*(0.13) + 72 = 73.3
For B:
10*(1.04) + 72 = 82.4
C) Do you think that this method of assigning grades is a good one?
Yes, it is good in terms of expressing scores around the mean such that score below are negative and those above are positive. However, it is a little bit ambiguous.
