exam one review

A researcher at a large company has collected data on the beginning salary and current salary of 48 randomly selected employees. The least-squares regression equation for predicting their current salary from their beginning salary is = -2532.7 + 2.12x. - Mrs. Kathy Jones started working for the company earning $19,000. She currently earns $40,000. What is the residual for Mrs. Jones?

B) $2252.70

The least-squares regression line always passes through the point ____.

B) (x bar, y bar)

A well-known maker of jams and jellies packages its jams in jars labeled "250 milliliters." The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What proportion of jars will be filled with what the label claims is 250 milliliters?

B) 0

What proportion of the statistics students in this class are sophomores?

B) 0.202

What proportion of the male voters is registered as a Democrat?

B) 0.30

The conditional distribution of Acceptable items produced by the three shifts is ______.

B) 0.345; 0.425; 0.230

The data are to be summarized by constructing marginal distributions. In the marginal distribution for car size, the entry for medium cars is ______.

B) 0.409

What proportion of the sampled females is in favor of more movies on campus?

B) 0.5

What is a plausible value for the correlation between lactic acid concentration and taste rating?

B) 0.7

A well-known maker of jams and jellies packages its jams in jars labeled "250 milliliters." The process used to fill the jars is known to dispense an amount of jam that is Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What proportion of jars from this filling process will contain no more than 253.5 milliliters?

B) 0.9522

A well-known maker of jams and jellies packages its jams in jars labeled "250 milliliters." The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What proportion of the jars filled by the process will contain less than 250 milliliters?

D) 0.0131

Items produced by a manufacturing process are supposed to weigh 90 grams. However, there is variability in the items produced, and they do not all weigh exactly 90 grams. The distribution of weights can be approximated by a Normal distribution with a mean of 90 grams and a standard deviation of 1 gram. What percentage of the items will either weigh less than 87 grams or more than 93 grams?

D) 0.3%

What proportion of the sampled males is in favor of more movies on campus?

D) 0.6

Using the standard Normal distribution tables, what is the area under the standard Normal curve corresponding to Z > -1.22?

D) 0.8888

The preparation time to mail envelopes with a weekly report to all executives in a company has a Normal distribution with a mean of 35 minutes and a standard deviation of 2 minutes. On 95% of such occasions, the mailing preparation takes less than x minutes. What is the value of x?

D) 38.29

What is the median for the number of home runs for the American League teams?

D) 57.5

Scatterplots can be used to determine ______ relationships between variables.

D) All of the above

Is age a good predictor of salary?

D) No, the correlation and r2 is low.

Consider the following data which describe the amount of time in minutes students spend studying for a quiz: 10, 11, 11, 12, 12, 14, 15, 18, 19, 20, 22, 24, 39, 40, 41, 44, 46, 50, 52, 52, 53, 55, 70. What numbers make up the leaf of the last stem?

D) None of the above

The number of Facebook friends students at a university have are Normally distributed with a mean of 1200 and a standard deviation of 200. What percentage of students has exactly 1000 Facebook friends?

D) None of the above

Below is a data set with information on students in a basic statistics class at a local university. What is a key characteristic of the data set?

D) all of the above

A description of different houses on the market includes the following three variables. Which of these variables is quantitative?

D) all the above

Categorical variables are best displayed by ______.

D) pie charts or bar graphs

When making a stemplot, it is appropriate to _______ if the values have many digits.

D) trim the leaves

The variable Z has a standard Normal distribution. Find the value z such that the event Z > z has a proportion of 0.08

D) z = 1.41

The variable Z has a standard Normal distribution. Find the value z such that 85% of the observations fall below z.

D) z= 1.04

Which of the following provides the best interpretation of the slope of the regression line?

E) If Goals Allowed increases by one goal, the Winning Percent decreases by 0.26%.

When examining a distribution of a quantitative variable, which of the following features do we look for?

E) all of the above

This plot is a graph of a(n) _____________, and it shows that there is/are ___________ in the data.

E) time series; a decreasing trend

The Michigan Department of Transportation (M-DOT) is working on a major project: 80% of the highways in Michigan need to be repaved. To speed completion of this project, many contractors will be working for M-DOT. Contractors are currently bidding on the next part of the project. To help make a decision about which contractor to hire, M-DOT collects many variables besides just the estimated cost. One of those variables is the contractor's estimate of the number of workdays required to finish the job. Twenty contractors have bid on the next job. The boxplot below represents their estimates of the number of work days required. What is (approximately) the interquartile range, based on the boxplot?

B) 270 days

- In a study of cars that may be considered classics (all built in the 1970s), the least-squares regression line of mileage (in miles per gallon) on vehicle weight (in thousands of pounds) is calculated to be mileage = 45 - 7.5 × weight - The mileage for a small Chevy is predicted to be 22 miles per gallon. What was the weight of this car?

B) 3067lbs.

A company produces packets of soap powder labeled "Giant size 32 ounces." The actual weight of soap powder in such a box has a Normal distribution with a mean of 33 ounces and a standard deviation of 0.7 ounces. To avoid dissatisfied customers, a box of soap is considered underweight if it weighs less than 32 ounces. To avoid losing money, the top 5% (the heaviest 5%) is labeled overweight. How heavy does a box have to be in order for the box to be labeled overweight?

B) 31.85 ounces

For the Winning Percent and Goals Allowed least-squares regression analysis above, which of the following statements is/are TRUE?

B) About 69% of the variation in the variable Winning Percent can be explained by the least-squares regression of Winning Percent on Goals Allowed.

What are possible reasons for a correlation around .13 for this problem?

B) Age is not a good predictor and something else may be a better a predictor

We have a data set where the cases are college students. One of the variables in the data set is "gender." The values of gender are 1 if the student is male and 2 if the student is female. What type of variable is gender?

B) Categorical

Suppose you own a pizza delivery company and you are trying to determine the best campus on which to sell pizza. What would be the best measurement to make the comparison?

B) Count of pizzas purchased

Which of the following statements about a scatterplot is/are TRUE?

B) On a scatterplot we look for overall patterns showing the form, direction, and the shape of the relationship.

By observing the scatterplot, what were you expecting the correlation to be?

B) The correlation would be weak based on the scatterplot.

Which of the following statements is/are FALSE?

B) The only relationship that a scatterplot can usefully display is linear with no outliers.

Suppose you wanted to predict the salary of the CEO of Facebook, Mark Zuckerberg, based on the information here. How well do you think your prediction would be assuming Mr. Zuckerberg was 23 when he started Facebook and became CEO?

B) The prediction would require extrapolation and therefore would not be accurate.

An outlier is ______.

B) a point in a scatterplot that does not follow the same pattern as the other points

A set of midterm exam scores has a median that is much larger than the mean. Which of the following statements is most consistent with this information?

B) a stemplot of the data would be skewed left

What is approximately the number of students with $30 or more in their possession?

B) about 10

From the histogram above, showing the distribution of MPG-City, we can see that the

B) distribution is skewed to the left

The tails of a distribution show the _______.

B) extreme values

Large data sets with quantitative variables are best displayed using ________.

B) histograms

The "direction" in scatterplots refers to the _________ direction.

B) positive and negative

When trying to explain the relationship between two quantitative variables, it would be best to use a _______.

B) scatterplot

- In a study of 1991 model cars, a researcher computed the least-squares regression line of price (in dollars) on horsepower. He obtained the following equation for this line. price = -6677 + 175 × horsepower - Based on the least-squares regression line, what would we predict the cost to be of a 1991 model car with horsepower equal to 200?

C) $28,323

The correlation, r, is a number between _______.

C) -1 ans 1

Considering the entire day's production of all sampled items, the proportion produced by Shift One that are Unacceptable is _________. Among items produced by Shift One, the proportion of Unacceptable items is __________.

C) 0.045; 0.127

What is the most plausible value for the correlation between spending on tobacco and spending on alcohol?

C) 0.08

In the conditional distribution for preference of car size among male respondents, the entry for large cars is _______.

C) 0.152

What proportion of registered Democrats is male?

C) 0.33

What proportion of the statistics students in this class are male?

C) 0.33

What proportion of the sampled students is in favor of more movies on campus?

C) 0.555

When using a pie chart, the sum of all the percentages should be _____.

C) 100

The median birth weight is approximately ________________.

C) 110 ounces

What percentage of the sampled female clients rated the tablet as not so easy to use (a rating of 4 or lower)?

C) 38%

The scores on a university examination are Normally distributed with a mean of 62 and a standard deviation of 11. If the bottom 5% of students will fail the course, what is the lowest mark that a student can have and still be awarded a passing grade?

C) 44

What is approximately the percentage of students with under $10 in their possession?

C) 44%

What is the mean for the number of home runs for the National League teams?

C) 50.1

Based on the graph, (approximately) how many of the sampled students graduated with a degree in Building/Construction or Architecture?

C) 65

What is the maximum number of home runs from a National League team?

C) 67

In a statistics course, a linear regression equation was computed to predict the final exam score from the score on the midterm exam. The equation of the least-squares regression line was (y hat = 10 + 0.9x) - where y represents the final exam score and x is the midterm exam score. Suppose Joe scores a 90 on the midterm exam. What would be the predicted value of his score on the final exam?

C) 91

Many residents of suburban neighborhoods own more than one car but consider one of their cars to be the main family vehicle. The age of these family vehicles can be modeled by a Normal distribution with a mean of 2 years and a standard deviation of 6 months. What percentage of family vehicles is between 1 and 3 years old?

C) 95%

A college newspaper interviews a psychologist about a proposed system for rating the teaching ability of faculty members. The psychologist says, "The evidence indicates that the correlation between a faculty member's research productivity and teaching rating is close to zero." What would be a correct interpretation of this statement?

C) Good researchers are just as likely to be good teachers as they are bad teachers. Likewise for poor researchers.

The scatterplot illustrates data from a basic statistics class. Students in the class were asked to provide the amount of time (in hours) they spent studying for the first exam. The professor then made a scatterplot to present the relationship between the number of hours a student studied and the score (from 0-100 with 100 being the best score) that the student received on the first exam. How would you interpret this scatterplot?

C) The correlation is likely a nonsense correlation caused by a lurking variable. Students who received higher scores likely did not need to study as much because they were doing better in the course than students who received lower scores

How do you interpret the intercept for this problem?

C) The intercept is not useful for this problem.

Variables measured on the same cases are _______ if knowing the values of one of the variables gives you information about the values of another variable that was not known beforehand.

C) associated

The lack of a linear relationship between two quantitative variables is represented by the correlation, r, with values ________.

C) equal to zero

Categorical variables place cases into ____ group(s)

C) many

If the number of reported malaria cases in Sierra Leone were mistyped and reported as 1,160,666, what would happen to the mean and median?

C) the mean and median would change

A particularly common question in the study of wildlife behavior involves observing contests between "residents" of a particular area and "intruders." In each contest, the residents either win or lose the encounter (assuming there are no ties). Observers might record several variables, some of which are listed below. Which of these variables is categorical?

C) whether the residents win or lose

If the number of reported malaria cases in Ghana in 2005 was mistyped and reported as 30,452,969, what would happen to the mean and median?

the mean would change, but the median would stay the same

The data are going to be summarized by computing the conditional distributions of year in school for male and female students. What would be the entry for male sophomores?

A) 0.065

A company produces packets of soap powder labeled "Giant size 32 ounces." The actual weight of soap powder in such a box has a Normal distribution with a mean of 33 ounces and a standard deviation of 0.7 ounces. To avoid dissatisfied customers, a box of soap is considered underweight if it weighs less than 32 ounces. To avoid losing money, the top 5% (the heaviest 5%) is labeled overweight. What proportion of boxes is underweight?

A) 0.0766

Using the standard Normal distribution tables, what is the area under the standard Normal curve corresponding to Z < 1.1?

A) 0.1357

What proportion of all voters is male and registered as a Democrat?

A) 0.15

The temperature at any random location in a kiln used for manufacturing bricks is Normally distributed with a mean of 1000°F and a standard deviation of 50°F. If bricks are fired at a temperature above 1125°F, they will crack and must be discarded. If the bricks are placed randomly throughout the kiln, what is the percentage of bricks that crack during the firing process?

A) 0.62%

In the plot, notice that length is treated as the response variable and width as the explanatory variable. Suppose we had taken width to be the response variable and length to be the explanatory variable. What would be the correlation between width and length in this case?

A) 0.827

The number of Facebook friends students at a university have are Normally distributed with a mean of 1200 and a standard deviation of 200. What percentage of students has at least 1000 Facebook friends?

A) 84.13%

A well-known maker of jams and jellies packages its jams in jars labeled "250 milliliters." The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with m = 252 milliliters and s = 0.9 milliliters. What percentage of jars will be filled with between 251 milliliters and 254 milliliters?

A) 85.3%

What percent of the variation in CEO salaries is explained by age alone?

A) Around 1.6%

The histogram below shows data from 30 students who were asked, "How much time do you spend on the Internet in minutes?" How could you improve the histogram to better display the distribution?

A) Increase the class size

Suppose a CEO is 57 years old. What do you predict his/her salary to be?

A) Over $400,000

We have a data set where the cases are college students. One of the variables in the data set is "grade." The values of grade are 4 if the student received an A, 3 if the student received a B, 2 if the student received a C, 1 if the student received a D, and 0 if the student received an A. What type of variable is grade?

A) Quantitative

A variable is a characteristic of a

A) case

To examine the relationship between two variables, the variables must be measured from the same _______.

A) cases

You can describe the overall pattern of a scatterplot by the _____.

A) form, direction, and strength

Least-squares regression can be used for prediction between explanatory and response variables that have a _______ relationship.

A) linear

The least-squares regression line is the line that ___________.

A) makes the sum of the squares of the vertical distance of the data points from the line as small as possible

59. A(n) ____ is an observation that is substantially different from the other observations.

A) outlier

. We have a data set where the cases are college students. One of the variables in the data set is "age of the student." What type of variable is age of the student?

A) quantitative

Variables that take numeric values for which arithmetic operations make sense are called _______.

A) quantitative

quantitative variables ae best displayed using ____.

A) stemplots

Below is a data set with information on students in a basic statistics class at a local university. Which variable is the label? (Student ID, GPA, Hometown, Major)

A) student ID

Researchers are conducting a state-wide survey for the U.S. Postal Service. The survey records many different variables of interest. Which of the following variables is categorical?

A) the countryside residence

What is approximately the number of burglaries in December 1989, the last date recorded in the timeplot?

A)22