Ch 3

A data set has Q1 = 12 and Q3 = 20. Which measurements in the set { -2, 1, 30, 31} would be considered outliers?

-2

Calculate the z score for the population value 6.5 where μ = 7.96 and σ = 0.42 (rounded to two decimals).

-3.84 Reason:(x−μ)/σ = (6.5−7.96)/0.42 = - 3.48

A data set has Q1 = 7 and Q3 = 11. Determine the lower and upper limits for a box plot.

1 and 17

Sam's exam score was good but 32% of students scored higher than Sam. That places Sam in the percentile.

68

A population has a mean of 50 and a standard deviation of 12. According to the empirical rule, approximately what percentage of the population data are contained between 38 and 62?

68%

Suppose that homework is worth 10%, quizzes 20%, and tests 70% of a final grade. If Joan has a homework grade of 92%, a quiz grade of 68%, and a test grade of 81%, then what is Joan's final grade?

79.5%

Calculate the mean of the following population data: 9, 8, 10, 10, 12, 6, 11, 10, 12, 8

9.6

Select all that apply Which of the following summaries portray grouped data?

A histogram A frequency distribution

True or false: In a weighted mean each measurement is given the same importance or weight.

False

Statistics describes _______________________ Parameters describes __________________________

Statistics describes samples Parameters describes populations

Which measure of central tendency is the same as the second quartile?

The median

True or false: The sample mean is the point estimate of the population mean.

True

A ______ is a graphical summary of a data set's quartiles and interquartile range.

box-and-whiskers display

The interquartile range is the difference between which two quartiles?

first and third

For populations that are positively or negatively skewed, the empirical rule tends to ______.

give unreliable descriptions of the distribution.

Which measure of central tendency is calculated by adding up all the measurements and then dividing by the number of measurements?

mean

A z score has units interpreted as _____________

standard deviations from the mean.

μ is the symbol used to denote: the population variance the sample variance the sample mean the population mean

the population mean

Standard deviation (the square root of variance) is expressed in _____ units as the original population.

the same

Population _____________ is the average of the squared deviations from the population mean.

variance

A ___________ mean is calculated by multiplying each measurement by its weight, summing the resulting products, and dividing the resulting sum by the sum of the weights.

weighted

A population value, x, has a z score of 3. What does this mean?

x is 3 standard deviations above the mean.

Arrange the steps (from first to last) to create a box-and-whiskers display.

1. Calculate Q1, Md, and Q3 2. Draw a box that extends from Q1 to Q3. Draw a vertical line through the box at Md. 3.Mark the values of the lower and upper limits 4. Draw the whiskers 5. Plot the outliers.

Which of the following symbols is used to denote mode?

Mo

In a box-and-whiskers display, the lower whisker is drawn from ____ to _____.

Q1; the smallest measurement that is not outlying.

The sample ______ is the average of the sample measurements.

mean

1st Quartile 2nd Quartile 3rd Quartile

1st Quartile matches 25th Percentile 2nd Quartile matches Median 3rd Quartile matches 75th Percentile

Using Chebyshev's Theorem, at least 93.75% of the population measurements lie within _______ standard deviations of the mean.

4

Given the following sample of ten numbers: 1, 4, 2, 5, 4, 4, 6, 4, 2, 1 The mode is 4. This is because:

4 occurs most frequently in the data set

Match the (x, y) pairs below with the most reasonable estimate of their correlation coefficient. (A) x = height of husband; y = height of wife (B) x = height of person; y = length of right arm (C) x = time spent studying for a quiz; y = number of points missed (D) x = height of person; y = score on history quiz

A matches 0.5 B matches 0.95 C matches -0.6 D matches 0

The coefficient of variation for Fund Z is 77.34. What does this mean?

The standard deviation is 77.34 percent of the mean.

When do we tend to calculate a sample covariance?

When we wish to measure the strength and direction of the linear association between two numerical variables.

Data summarized in frequency distribution or histogram form, without giving the individual measurements, is called __________ data.

grouped

In a neighborhood there are five houses listed for sale for the following amounts: $250,000, $275,000, $280,000, $295,000, and $515,000. What is the best measure of central tendency for the price of a house in the neighborhood?

median

Match the following pairs with the anticipated sign of their sample covariance.

negative matches X = amount of insulation; Y = winter heating bill near zero matches X = patient's height; Y = patient's systolic blood pressure positive matches X = person's height; Y = person's arm span

A population ______ is a number calculated using the population measurements that describes some aspect of the population.

parameter

A set of measurements is divided into four parts, each containing approximately 25% of the measurements. These three dividers are called?

quartiles

The ______________ of measurements in a data set is calculated as the largest measurement minus the smallest measurement.

range

The sample standard deviation can be found by ________________ the sample variance.

taking the square root of

The length of the interval that contains the middle 50% of measurements is known as ______.

the interquartile range

When calculating an approximate variance for grouped data, ______

the midpoint of each class is used to approximate the measurements in that class.

Calculate the mean of the following sample data: 1, 1, 1, 3, 6, 8, 8

4

Given the following sample of ten numbers: 1, 4, 2, 5, 4, 4, 6, 4, 2, 1 Compute the following: Md ______________

4

Which of the following statements about population variance and standard deviation are true? The more spread out the measurements in a data set are, the larger the variance will be. Variance is expressed in the same units as the original measurements. The raw deviations from the mean sum to zero. The more spread out the measurements in a data set are, the larger the standard deviation will be.

The more spread out the measurements in a data set are, the larger the variance will be. The raw deviations from the mean sum to zero. The more spread out the measurements in a data set are, the larger the standard deviation will be.