QMB Chpt 3 HW

The sample correlation coefficient can be equal to any value __________. other than zero greater than or equal to zero between -1.0 and +1.0 between -∞ and +∞

between -1.0 and +1.0

Comparing the consistency between two data sets when their means are very different is best done with the ________. standard deviation coefficient of variation median z-score

coefficient of variation

The ________ measures a distribution's standard deviation in terms of its percentage to the mean. variance median coefficient of variation z-score

coefficient of variation

According to the empirical rule, we would expect approximately 68, 95, and 99.7% of the values to fall within one, two, and three standard deviations above and below the mean respectfully for all distributions. t/f

false

Data Analysis ToolPak in Excel can be used to determine the mode for categorical data. t/f

false

In a quality control setting, the sample mean provides enough evidence to determine if a process is working properly t/f

false

The MODE SNGL function in Excel will correctly identify more than one mode in a data set

false

The sample standard deviation for grouped data provides an exact value for the sample standard deviation. True False

false

The unit of measure for the variance is the same as the unit of measure for the original data t/f

false

The average monthly rent for a two-bedroom apartment in City A is $820 with a standard deviation of $86. The average monthly rent for a two-bedroom apartment in City B is $790 with a standard deviation of $75. Based on this data, we can conclude that the rent for two-bedroom apartments in City A is more consistent when compared to City B. True False

false (coefficient of variation= sd/mean) 86/820 > 75/790

The ________ is found by first determining the index point, i = 0.5(n), where n is the number of data points. average mode median mean

median

The ________ is the value in the data set for which half the observations are higher and half the observations are lower. mean mode average median

median

When outliers are present in the data set, the ________ is the best choice to measure central tendency. mode median mean standard deviation

median

When working with grouped data, the ________ is the value in the middle of the class and can be found by taking the average of the endpoints for each class. range endpoint median midpoint

midpoint

The following table represents the number of seconds that a particular web page took to load on an iPhone for 25 users along with the frequency in each class. Seconds to Load- 0-Under 5, 5-Under 10, 10-Under 15, 15-Under 20, 20-Under 25 # of Phone Users- 4, 7, 3, 10, 1 What is the approximate average number of seconds that this web page took to load on the iPhone? 11.9 12.5 15.0 13.7

11.9 =(sumproduct(midpoints, numbers))/n

The average salary for a sales representative in a medical billing company is $46,600 with a standard deviation of $6,400. The coefficient of variation for salaries at this company is 11.7%. 16.4%. 13.7%. 9.0%.

13.7% (6400/46600)

The following data represents the ages of a household that consists of five people. Assume that the household is considered a population in this example. 39, 37, 12, 7, 7 The standard deviation of this data set is ________. 14.5 10.9 16.0 12.0

14.5 =stdev.p

Suppose the average price for new cars has a mean of $30,100 and a standard deviation of $5,600. Based on this information, what interval of prices would we expect at least 95% of new car prices to fall within?

18,900-41,300 (2 standard deviations)

The following data set represents the age of a random sample of cars on the road today. 1, 3, 3, 7, 10, 12 The variance of this sample is ________. 9.5 23.7 19.2 16.4

19.2 =var.s( )

The following data shows the number of home runs hit by the top 12 home run hitters during a recent Major League Baseball season. 43, 41, 39, 39, 38, 37, 37, 36, 34, 33, 33, 32 The interquartile range is ________. 5.5 4 7 4.5

5.5 (IQR=Q3-Q1.. the middle 50% of range)

The median is the ________ percentile in the data set. 25th 50th 75th 100th

50th

Suppose the wait through immigration at JFK airport is though to be bell-shaped and symmetrical with a mean of 22 minutes. It is known that 68% of travelers will spend between 16 and 28 minutes waiting to pass through immigration. The standard dev for the wait time through immigration is

6 minutes (one sd)

The following data represents the number of Sony TVs sold per day at a particular Costco over a random sample of five business days. 9, 2, 7, 7, 5 The mean of this sample is ________. 6.6 5.7 6.4 6.0

6.0

The daily high temperature in Philadelphia over an eight-day period is shown below. 69, 77, 70, 81, 84, 86, 69, 70 The median for this data set is ________. 77 70 73.5 69

73.5

There are five rows of students seated in a statistics class. The following table shows the number of students in each row and the average score of the most recent exam for that row. What is the average exam score for this class? 84.7 83.0 86.8 85.7

85.7

The following table represents the number of minutes that 20 airline passengers had to wait in order to pass through security along with the frequency in each class. (Excel) What is the approximate standard deviation for the number of minutes that a passenger waits to pass through security? 9.88 10.80 10.65 9.63

9.88

Suppose the nightly rate for a three-star hotel in Paris is thought to be bell-shaped and symmetrical with a mean of 160 euros and a standard deviation of 8 euros. The percentage of hotels with rates between 144 and 176 euros is

Approximately 95 (Empirical Rule- 68, 95, 99.7)

The ________ is the most common and most important measure of variability in the field of statistics. standard deviation range variance median

standard deviation

A negative sample covariance indicates that as one variable increases in value, the second variable tends to decrease. True False

true

A weighted mean allows you to assign more weight to certain values and less weight to others. t/f

true

Chebyshev's Theorem states that for any number z greater than 1, the percent of the values that fall within z standard deviations from the mean will be at least (1-1/z^2)*100 t/f

true

If the data set does not have a mode, Data Analysis ToolPak in Excel displays "#N/A" in the spreadsheet cell

true

Measures of variability shows how much spread is in your data t/f

true

Outliers are extreme values above or below the mean that require special consideration t/f

true

Percentiles measure the approximate of values in the data set that are below the value of interest t/f

true

The central tendency is where the majority of the data points can be found in a histogram t/f

true

The mean is a convenient measurement for summarizing a data set with a single value t/f

true

The sample correlation coefficient can be a positive value, a negative value, or zero. True False

true

The sample covariance measures the direction of the linear relationship between two variables. True False

true

There can be more than one mode in a data set; Some data sets may not have a mode t/f

true

When comparing two samples, the smaller coefficient of variation indicates more consistency (or less variability) within the sample or population t/f

true

When using the index point, i, to determine the pth percentile of a data set, round i to the next whole number if i=(p/100)*k is not a whole number t/f

true

The ____ measures the variability, or spread, of a data point in a set around the set's mean

variance

The ______ identifies the number of standard deviations a particular value is from the mean of its distribution

z-score

The average class size this semester in the business school of a particular university is 38.1 students with a standard deviation of 12.9 students. The z-score for a class with 21 students is ________. -1.33 0 1.51 0.80

z= (x-mean)/sd -1.33

Consider the following data set: Variable 1: 20, 15, 14, 10, 5, 5, 8, 3 Variable 2: 2, 9, 5, 3, 8, 10, 17, 10 The sample correlation coefficient for this data set is __________. 0.18 -0.55 -0.80 0.47

-0.55 =correl()

The following data represents the number of Sony TVs sold per day at a particular Costco over a random sample of five business days. 9, 2, 7, 7, 5 The standard deviation of this sample is ________. 1.5 2.0 2.6 1.2

2.6

The following table shows a frequency distribution of the number of MacBook Air laptops sold per day at a particular Best Buy. # laptops- 0, 1, 2, 3, 4, 5 frequency- 2, 5, 3, 8, 5, 2 What is the mean number of MacBook Air laptops sold per day? 3.0 3.9 2.6 3.5

2.6

The first quartile represents the ________ percentile of the data set. 50th 75th 25th 10th

25th

The MCAT is the admission exam that medical schools use as one of the criteria for accepting students. The exam is based on a scale of 0-45. The following data shows the MCAT scores for nine students. 32, 36, 29, 31, 30, 35, 34, 26, 30 The 35th percentile of this data set is ________. 31.5 31 32 30

30

A random sample of 20 cars was selected. The following table shows the number of cars grouped by age in years. Age in Yrs- 0-Under 4, 4-Under 8, 8-Under 12, 12-Under 16 # of Cars- 7, 2, 8, 3 What is the approximate standard deviation for the age of cars from this sample? Round to one decimal place. Approximate average age of cars?

4.5 ; 7.4

The following data represents the actual talk time, in hours, for the Samsung smartphone for 11 users. 25.1, 19.1, 21.6, 9.5, 20.3, 18.0, 24.6, 25.2, 21.9, 29.7, 28.5 What percentile is the talk time of 21.6 hours? Use the formula, not the Excel function. 41st 54th 58th 49th

41st (# Values below 21.6+0.5)/ total values (PERCENTILE RANK)