Exam 3: Descriptive Statistics: Numerical Measures

Exhibit 3-4 The following is the frequency distribution for the speeds of a sample of automobiles traveling on an interstate highway. Speed Miles per Hour Frequency 50-54 2 55-59 4 60-64 5 65-69 10 70-74 9 75-79 5 35 -Refer to Exhibit 3-4. The standard deviation is

Given the following information: Standard deviation = 8 Coefficient of variation = 64% The mean would then be

A numerical measure of linear association between two variables is the

If the coefficient of variation is 40% and the mean is 70, then the variance is

Global Engineers hired the following number of Class 1 engineers during the first six months of the past year. Assume the data represent a sample.) No. of Class 1 Month Engineers Hired January 3 February 2 March 4 April 2 May 6 June 0 a. Determine the mean, the median, the mode, and the range for the above data. b. Compute the variance and the standard deviation. c. Compute the first and the third quartiles. d. Compute the z-scores for the months of May and June.

The following is a frequency distribution of grades of a sample of statistics examinations. grade Frequency 50-59 7 60-69 10 70-79 22 80-89 15 90-99 6 Compute the following measures: a. The mean b. The variance c. The standard deviation d. The coefficient of variation

Exhibit 3-3 A researcher has collected the following sample data. The mean of the sample is 5. 3 5 12 3 2 -Refer to Exhibit 3-3. The interquartile range is

For 27 days, the temperature in Fairbanks, Alaska has been below zero. Thus, the mean temperature has been negative. In this situation, the standard deviation must be

From a population of size 1,000, a random sample of 100 items is selected. The mean of the sample

The 50th percentile is the

The flashlight batteries produced by one of the northern manufacturers are known to have an average life of 60 hours with a standard deviation of 4 hours. Use Chebyshev's theorem to answer the following questions. a. At least what percentage of flashlights will have a life of 54 to 66 hours? b. At least what percentage of the batteries will have a life of 52 to 68 hours? c. Determine an interval for the batteries lives that will be true for at least 80% of the batteries. Hint: First compute the Z-score.)

For the following frequency distribution, Class Frequency 45-47 3 48-50 6 51-53 8 54-56 2 57-59 1 a. Compute the mean. b. Compute the standard deviation. Assume the data represent a population.)

The standard deviation of a sample was reported to be 7. The report indicated that = 980. What has been the sample size?

Exhibit 3-3 A researcher has collected the following sample data. The mean of the sample is 5. 3 5 12 3 2 -Refer to Exhibit 3-3. The variance is

The pth percentile is a value such that at least p percent of the observations are

For the following frequency distribution assume the data represent a population), Class Frequency 70-79 5 80-89 9 90-99 11 100-109 9 110-119 6 a. Compute the mean. b. Compute the standard deviation.

Exhibit 3-6 The closing stock price of MNM Corporation for the last 7 trading days is shown below. Day Stock Price 1 84 2 87 3 84 4 88 5 85 6 90 7 91 -Refer to Exhibit 3-6. The mode is

During a cold winter, the temperature stayed below zero for ten days ranging from -20 to -5). The variance of the temperatures of the ten-day period

The number of hours worked per week for a sample of ten students is shown below. student Hours 1 20 2 0 3 18 4 16 5 22 6 40 7 8 8 6 9 30 10 40 a. Determine the median and explain its meaning. b. Compute the 70th percentile and explain its meaning. c. What is the mode of the above data? What does it signify?

The relative frequency of a class is computed by