C

D

Sample size

198

158

Get to the bottom of the grades

8.05 (7.30 - 8.80)

8.60 (7.78 - 9.30)

Measured results

7.80 (7.10 - 8.50)

8.40 (7.60 - 8.90)

With

−8.859

−4.833

P

<0.05

<0.05