Exam 3: Describing Data Using Numerical Measures

A distribution has a coefficient of variation of 65 percent and mean of 74.What is the value of the standard deviation?

Consider the following sample data: For these data the median is:

The marketing manager for Voice-talk,a cell phone company,has taken a sample of 300 customers from the list of 4,356 total customers.The mean monthly bill for the last October based on the sample data is $45.62.The manager should realize that the mean bill for all 4,356 customers will actually be higher than $45.62.

Recently an article in a newspaper stated that 75 percent of the households in the state had incomes of $20,200 or below.Given this input,it is certain that mean household income is less than $20,200.

Consider the following data,which represent the number of miles that employees commute from home to work each day.There are two samples: one for males and one for females. Males: Females: Which of the following statements is true?

If a population standard deviation is computed to be 345,it will almost always be the case that a standard deviation computed from a random sample from that population will be larger than 345.

In comparing two distributions with the same mean,the coefficient of variation is the only way to assess which distribution has the greatest relative variability.

At a sawmill in Oregon,a process improvement team measured the diameters for a sample of 1,500 logs.The following summary statistics were computed: Given this information,the boundaries on the box in a box and whisker plot are:

One of the primary advantages of using the median as a measure of the center for a set of data is that the median is not affected by extreme values in the data.

The symbol μ is used to represent the sample mean.

Each year,Business Week publishes information and rankings of master of business administration (MBA)programs.The data file MBA Analysis contains data on several variables for eight reputable MBA programs as presented in the October 2,2000,issue of Business Week.The variables include pre- and post-MBA salary,percentage salary increase,undergraduate GPA,average Graduate Management Admission Test (GMAT)score,annual tuition,and expected annual student cost.Compute the mean and median for each of the variables in the database.

The following data reflect the number of customers who test drove new cars each day for a sample of 20 days at the Redfield Ford Dealership. Given these data,what is the variance?

A major automobile maker has two models of sedans.The first model has been shown to get an average of 27 mpg on the highway with a standard deviation equal to 5 mpg.The second model gets 33 mpg on average with a standard deviation of 8 mpg.Based on this information the first car model is relatively more variable than the second car model.

If a data set has 1,133 sorted values,what value corresponds to the 3^rd quartile?

The Parks and Recreation manager for the city of Detroit recently submitted a report to the city council in which he indicated that a random sample of 500 park users indicated that the average number of visits per month was 4.56.This value should be viewed as a statistic by the city council.

Incomes in a particular market area are known to be right-skewed with a mean equal to $33,100.In a report issued recently,a manager stated that at least 89 percent of all incomes are in the range of $26,700 to $39,500,and this was based on Tchebysheff's theorem.Given these facts,what is the standard deviation for the incomes in this market area?

The distribution of dollars paid for car insurance by car owners in a major east coast city is bell-shaped with a mean equal to $750 every six months and a standard deviation equal to $100.Based on this information we should use Tchebysheff's theorem to determine the conservative percentage of car owners that will pay between $550 and $950 for car insurance.

Dynamic random-access memory (DRAM)memory chips are made from silicon wafers in manufacturing facilities through a very complex process called wafer fabs.The wafers are routed through the fab machines in an order that is referred to as a recipe.The wafers may go through the same machine several times as the chip is created.The data file DRAM Chips contains a sample of processing times,measured in fractions of hours,at a particular machine center for one chip recipe. Calculate the 80th percentile for processing time.

If a business manager selected a sample of customers and computed the mean income for this sample of customers,she has computed:

A statistic is a value that describes a population characteristic while a parameter is computed from a sample.