A

B

C

D

And

Sample size

100

99

98

72

100

Get to the bottom of the grades

6.00 (2.00 - 10.00)

5.00 (0.00 - 10.00)

6.00 (2.00 - 12.00)

5.50 (1.00 - 10.00)

6.00 (3.00 - 11.00)

Measured results

8.50 (4.00 - 13.00)

6.00 (2.00 - 12.00)

10.00

(3.00 - 17.00)

6.00 (1.00 - 10.75)

7.00 (3.00 - 15.00)

With

−6.727

−5.661

−5.62

−1.878

−5.256

P

<0.05

<0.05

<0.05

0.60

<0.05