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) 250 students earned more than $30,000.
(ii. 500 students earned between $20,000 and $40,000.
(iii) 3 students earned less than $22,500.
A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (i) and (ii) are correct statements but not (iii).
E) (ii) and (iii) are correct statements but not (i).

Question

Quizplus · Accepted Answer

(i) and (ii) are true because the mean is $30,000 and the standard deviation is $3,000. (iii) is also true because 3 standard deviations below the mean is $22,500.

A Sample of 500 Evening Students Revealed That Their Annual