A sample of 500 evening students revealed that their annual incomes from employment in industry during the day were normally distributed with a mean income of $30,000 and a standard deviation of $3,000.
i) How many students earned more than $30,000?
ii) How many students earned between $27,000 and $33,000?
iii) How many students earned less than $22,500
Select one
a) ii and iii are correct statement but not one
b) i is a correct statement but not ii or iii
c) i and ii are correct statement but not iii
d) I , ii and iii are all correct statements
e) i and iii are correct statements but not ii