Question

Here are the total scores of 10 students in an introductory statistics course.

Answer 1

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.