Question

Select the CORRECT statements.

		Given the variance of 5.78, the standard deviation is 7.73.
		The coefficient of variation is equal to 150% when the mean is 8 and the standard deviation is 12.
		Prices are the example of the nominal scale of measurement.
		Given a normal (bell-shaped) distribution with the mean of 12 and the standard deviation of 4, approximately 2.5% of observations will be above 20.
		It is usually a good idea to have more than 35 classes in a frequency table (or a histogram).

Answer 1

Ans:
1. Correct
Coefficient of variation = S.D/mean = 12/8 = 1.5 or 150%

2. Wrong
Generally making of 6 to 15 number of classes is a good idea for a frequency table

3. Correct
Mean = 12
S.D = 4
X = 20
z = (X-Mean)/S.D = (20 - 12)/4 = 2
P(X>20) = 2.5% (From standard normal table)

4. Wrong
Prices are the ratio scale of data

5. Wrong
Variance = (S.D)^2
But here the above condition is not satisfied