Exam 5: Numerical Descriptive Measures

The coefficient of variation is the standard deviation divided by the mean.

Data were obtained for the weight in grams, of a sample of 10 packets of sweetener, as found in cafés. 4.5 5 5.9 5.4 5.5 4.7 4.9 4.7 4.7 4.6 Find the range

The relative frequency histogram for the age (in years) of a sample of 25 employees from a government department, is given below. Explain what the best measure of variability is.

The following data represent the salaries (in thousands of dollars) of a sample of 13 employees of a firm: 26.5 23.5 29.7 24.8 21.1 24.3 20.4 22.7 27.2 23.7 24.1 24.8 28.2 Compute the 90th percentile.

Which of the following best describes the width of the box in the box-and-whisker plot?

The value of the standard deviation will always exceed that of the variance.

The following data represent the weights (in kilograms) of a sample of 30 horses: Weight 165 175 150 155 173 149 145 153 153 153 152 145 164 143 170 175 148 174 171 156 166 168 152 150 173 168 146 155 172 159 Calculate the 3rd and 8th deciles of the data.

The following data represent the ages (in years) of a sample of 25 employees from a government department: 31 43 56 23 49 42 33 61 44 28 48 38 44 35 40 64 52 42 47 39 53 27 36 35 20 The frequency distribution for the data, using five class intervals and the value 20 as the lower limit of the first class is given below. Class Limits Frequency 20 up to 30 4 30 up to 40 7 40 up to 50 9 50 up to 60 3 60 up to 70 2 Total 25 Find the mean of the grouped data.

Which of the following would be the value of the correlation coefficient of two variables which are not linearly related.

The following data represent the ages (in years) of a sample of 25 employees from a government department: 31 43 56 23 49 42 33 61 44 28 48 38 44 35 40 64 52 42 47 39 53 27 36 35 20 Compute the interquartile range of the data.

If the coefficient of correlation r = +1, then the best-fit linear equation will actually be satisfied by all of the data points.

The coefficient of determination measures the percentage of variation in the independent variable explained by the dependent variable.

Which of the following statements is true?

The shape of the distribution helps to determine the best measure of central location and variability in a data set.

A linear regression model estimating the relationship between Expenditure on imports($) and Annual household income($) is as follows: Estimated Expenditure on Imports = 1.35 + 0.11Annual household income. Interpret the slope.

In a negatively skewed distribution, the mean is greater than the median.

What measure of central location is best used with a categorical variable?

A courier company is reviewing their delivery times. The following descriptive statistics relates to this courier company. The mean time for package delivery is 5 hours, the first quartile is 4 hours, the third quartile is 17 hours. This means that the median must lie between 4 hours and 17 hours.

In a negatively skewed distribution, the mean is smaller than the median and the median is smaller than the mode.

The following data represent the ages (in years) of a sample of 25 employees from a government department: 31 43 56 23 49 42 33 61 44 28 48 38 44 35 40 64 52 42 47 39 53 27 36 35 20 Compute the range approximation to the standard deviation of the data. (Hint: S $\approx$ Range/4