I have this question which i am so confused how to solve it
this is on normal curve. The following table is used to determine the student’s grades:
Grade Z-score A above 1.5 B 0.5-1.5 C -0.5 to 0.5 D -1.5 to -0.5 F Below-1.5
Using this system, what percent of As Bs, Cs Ds and Fs are expected with a normal distribution of scores?
Now, I know the distribution is distributed in -2.1% - 13.4% - 34.1% (on both sides). It would have been easier if i could imagine that mean is 0 and sd is 1. but the above distribution doesn't match if i assume SD is 1 since the gap between 0.5 is 1 and then its 1 and so on (not sure if i am making any sense, I am just trying to think).
I am unable to put a finger how to go about this problem.