You can’t do this. That’s is not mathematically correct
Have you found the answer to this??
Z score = 66 - 76
---------- = - 1
10
from the tables of normal distribution this corresponds to 0.34-3 of the area under the normal curve
so reuired number od students = 0.3413 * 230 = 78
-9+x ?
I don’t know if this is the right answer
