Exam 2: Methods for Describing Sets of Data

Many firms use on-the-job training to teach their employees computer programming. Suppose you work in the personnel department of a firm that just finished training a group of its employees to program, and you have been requested to review the performance of one of the trainees on the Final test that was given to all trainees. The mean and standard deviation of the test scores are 79 and 2, respectively, and the distribution of scores is mound-shaped and symmetric. Suppose the trainee in question received a score of 76. Compute the trainee's z-score. A) $z = 0.94$ B) $z = - 1.50$ C) $z = - 6$ D) $z = - 3$

The calculator screens summarize a data set. a. Identify the smallest measurement in the data set. b. Identify the largest measurement in the data set. c. Calculate the range of the data set.

Which is expressed in the same units as the original data, the variance or the standard deviation?

The test scores of 30 students are listed below. Which number could be the 30th percentile? 31 41 45 48 52 55 56 56 63 65 67 67 69 70 70 74 75 78 79 79 80 81 83 85 85 87 90 92 95 99

The calculator screens summarize a data set. a. Identify the mean and the sample standard deviation. Round to one place after the decimal, where necessary. b. Find the interval that corresponds to measurements within two standard deviations of the mean.

A study was designed to investigate the effects of two variables - (1) a student's level of mathematical anxiety and (2) teaching method - on a student's achievement in a mathematics course. Students who had a low level of mathematical anxiety were taught using the traditional expository method. These students obtained a mean score of 440 with a standard deviation of 50 on a standardized test. Assuming a mound-shaped and symmetric distribution, in what range would approximately 68% of the students score?

Each year advertisers spend billions of dollars purchasing commercial time on network television. In the first 6 months of one year, advertisers spent $1.1 billion. Who were the largest spenders? In a recent article, the top 10 leading spenders and how much each spent (in million of dollars) were listed: Company A \ 71 Company F \ 25.9 Company B 63.7 Company G 24.6 Company C 54.5 Company H 23.1 Company D 54.1 Company I 23.6 Company E 28.5 Company J 19.8 Calculate the mean and median for the data.

The scores of nine members of a women's golf team in two rounds of tournament play are listed below. Player 1 2 3 4 5 6 7 8 9 Round 1 85 90 87 78 92 85 79 93 86 Round 2 90 87 85 84 86 78 77 91 82 Construct a scattergram for the data.

Parking at a university has become a problem. University administrators are interested in determining the average time it takes a student to find a parking spot. An administrator inconspicuously followed 90 students and recorded how long it took each of them to find a parking spot. Which of the following types of graphs should not be used to display information concerning The students parking times?

A dot plot of the speeds of a sample of 50 cars passing a policeman with a radar gun is shown below. What proportion of the motorists were driving above the posted speed limit of 55 miles per hour?

A radio station claims that the amount of advertising each hour has a mean of 15 minutes and a standard deviation of 1.5 minutes. You listen to the radio station for 1 hour and observe that the amount of advertising time is 9 minutes. Calculate the z-score for this amount of advertising time. A) $z = - 4.00$ B) $z = - 9$ C) $z = 0.50$ D) $z = 4.00$

The output below displays the mean and median for the state high school dropout rates in year 1 and in year 5. Year 1 Year 5 N 51 51 MEAN 28.22 26.56 MEDIAN 27.53 25.18 Use the information to determine the shape of the distributions of the high school dropout rates in year 1 and year 5.

All class intervals in a histogram have the same width.

Each year advertisers spend billions of dollars purchasing commercial time on network television. In the first 6 months of one year, advertisers spent $1.1 billion. Who were the largest spenders? In a recent article, the top 10 leading spenders and how much each spent (in million of dollars) were Listed: Company A \ 70.7 Company F \ 24.8 Company B 63.9 Company G 24 Company C 55.7 Company H 22.7 Company D 54.2 Company I 23.2 Company E 30.3 Company J 20.1 Calculate the sample variance.

A shoe retailer keeps track of all types of information about sales of newly released shoe styles. One newly released style was marketed to tall people. Listed below are the shoe sizes of 12 randomly selected customers who purchased the new style. Find the mode of the shoe sizes. 9 11 12 11 8 10 8 11 10 11 9 10

A sociologist recently conducted a survey of senior citizens who have net worths too high to qualify for Medicaid but have no private health insurance. The ages of the 25 uninsured senior citizens were as follows: 72 77 70 80 90 78 65 93 69 94 73 96 80 66 85 67 72 85 74 77 64 91 79 68 86 Find the median of the observations.

What is the primary advantage of a time series plot?

The scatterplot below shows a negative relationship between two variables.

The range is an insensitive measure of data variation for large data sets because two data sets can have the same range but be vastly different with respect to data variation.

The amount of time workers spend commuting to their jobs each day in a large metropolitan city has a mean of 70 minutes and a standard deviation of 20 minutes. Assuming the distribution of commuting times is known to be moundshaped and symmetric, what percentage of these commuting times are between 50 and 110 minutes?