Question

1. The January utility bills (in dollars) for 20 residents of a large city are listed below.  

70 72 71 70 69 73 69 68 70 71

            67 71 70 74 69 68 71 71 71 72

a) Find the range of the data. (Circle the correct answer)

A) $2 B) $2.98 C) $7 D) $1.73

b) Find the standard deviation of the data. (Circle the correct answer)

A) 2.35 B) 1.24 C) 2.51 D) 1.73

2. In the computation of the sample standard deviation, how many degrees of freedom are there in a data set that has 15 data values? (Circle the correct answer)

A) 14 B) 15 C) 16 D) None of these

3. Which is not a measure of dispersion? (Circle the correct answer)

A) Variance B) Standard Deviation C) Mean D) Range

Answer 1

a)

range =max -min =74-67 =7

option C is correct

b)

standard deviation =1.73

option D

c)

degree of freedom =n-1=15-1 =14

d)

not a measure of dispersion : mean

option C