Deck 10: Standard Deviation

Question 1

Why is the standard deviation often considered a better measure of dispersion than the mean deviation?

A) It is more accurate
B) It is easier to understand
C) It does not require the modulus sign
D) It can be written as a formula

Answer 1

It does not require the modulus sign

Question 2

How might the variability of two distributions be compared assuming the means are not similar?

A) Use the coefficient of variation
B) Take smaller standard deviation from the larger
C) Compare the squares of the standard deviations
D) You cannot compare data sets in this way

Answer 2

Use the coefficient of variation

Question 3

Which of the following statements about the standard deviation IS true?

A) It is closely associated with the median
B) If the distribution is not too skewed, most values lie within 2 standard deviations of the mean
C) As all the data points are taken into account it is representative of the data
D) Half of all data points are within 1 standard deviation of the mean if the distribution is not too skewed

Answer 3

As all the data points are taken into account it is representative of the data

Question 4

Calculate the coefficient of variation for a data set where the mean is 3 and the standard deviation is 0.5 (1 decimal place).

A) 16.5%
B) 16.6%
C) 16.7%
D) 16.8%

Question 5

Calculate the standard deviation (2 decimal places) from the following set of data: 4, 8, 12, 16

A) 4.00
B) 4.28
C) 4.36
D) 4.47

Question 6

A double glazing firm compares the number of windows in customers' orders in one month and produces the following data [number of windows(frequency)]: 0 to 2(15); 3 to 5(6); 6 to 8(3). Calculate the standard deviation of this data (2 decimal places).

A) 7.10
B) 7.20
C) 7.30
D) 7.40

Question 7

The mean price of a house in Bristol is £210,000 . In which city do house prices vary more?

A) Bristol
B) Milan
C) They are the same
D) You cannot tell

Question 8

Calculate Pearson's measure of skewness for data that has a mean of 8, a mode of 4 and a standard deviation of 0.8

A) 5
B) -5
C) 2.5
D) -2.5

Question 9

In a flour mill 6 bags of flour are weighed to check for consistency. The weights of the bags are 0.95kg, 1.00kg, 1.10kg, 1.05kg, 0.95kg, 1.10kg. Calculate the standard deviation of these samples (2 decimal places)

A) 0.06
B) 0.07
C) 0.08
D) 0.09

Question 10

You are told that wage levels are skewed to the right. What does this tell you about the value for Pearson's measure of skewness?

A) It is less than 0
B) It is 0
C) It is greater than 0
D) You cannot tell