STP Module 2-4

Find the mean for the given sample data. Unless otherwise specified, round your answer to one more decimal place than that used for the observations. The grocery expenses for six families were 55.72, 55.08, 76.11, 54.18, 63.56, 85.72 Compute the mean grocery bill. Round your answer to the nearest cent.

$65.06

The average score on an aptitude test is 80 with a standard deviation of 10. One person scored a 65. What is that person's z-score?

-1.5

Find the sample standard deviation for the given data. Round your final answer to one more decimal place than that used for the observations. The manager of a small dry cleaner employs six people. As part of their personnel file, she asked each one to record to the nearest one-tenth of a mile the distance they travel one way from home to work. The six distances are listed below. 24.6 14.1 39.9 48.0 18.5 17.1

13.78 mi

A nurse measured the blood pressure of each person who visited her clinic. Following is a relative-frequency histogram for the systolic blood pressure readings for those people aged between 25 and 40. Use the histogram to answer the question. The blood pressure readings were given to the nearest whole number. Given that 300 people were aged between 25 and 40, approximately how many had a systolic blood pressure reading between 140 and 149 inclusive?

24 (.08*300)

The variance for a sample was found to be 49. What is the sample standard deviation?

7 (square root of 49)

Suppose we have 10 exam scores for an introductory statistics course. The scores are 78, 98, 94, 89, 86, 77, 76, 80, 75, 68. The median score is

79

Use the regression equation to predict the y-value corresponding to the given x-value. Round your answer to the nearest tenth. The regression equation relating attitude rating (x) and job performance rating (y) for ten randomly selected employees of a company is y hat = 11.7+1.02x. Predict the job performance rating for an employee whose attitude rating is 67.

80.0

An indication of no linear relationship between two variables would be:

A correlation coefficient equal to 0

Here are 3 boxplots of weekly gas prices at a service station in the United States (price in $ per gallon). Compare the distribution of prices over the three years.

Gas prices have been increasing on average over the 3-year period, and the variation overall has been increasing as well. The distribution has been right-skewed, and there were 3 potential outliers in 2005.

A linear regression line was constructed relating two variables, x, and y where X is the independent variable and y is the response (dependent variable). The slope was found to be 20 and the intercept was found to be -4. Based on this information, predict the value of y when x = 2

NOT 12 ANSWER: C. 36

In publishing the results of some research work, the following values of the correlation coefficient were listed. Which one would appear to be incorrect? A. 1.2 B. 0.90 C. -0.8 D. 0

NOT C. (-0.8) ANSWER: A. 1.2

Identify the study as an observational study or a designed experiment. An educational researcher used school records to determine that, in one school district, 84% of children living in two-parent homes graduated high school while 75% of children living in single-parent homes graduated high school.

Observational study

Classify the data as either qualitative or quantitative. The following table gives the top five movies at the box office this week. Rank-last week-movie title-studio-sales (millions$) What kind of data is provided by the information in the first column?

Quantitative

In a poll of 50,000 randomly selected college students, 74% answered "yes" when asked "Do you have a television in your dorm room?" Identify the sample and population.

Sample: the 50,000 selected college students; population: all college students

A graphical display of a data set is given. State whether the distribution is (roughly) symmetric, right skewed, or left skewed. Two dice were rolled and the sum of the two numbers was recorded. This procedure was repeated 400 times. The results are shown in the relative frequency histogram below.

Symmetric

A political pollster reports that her candidate has a 5% lead in the polls. This is an example of

an Observational Study

Height is a

continuous variable

Determine the regression equation for the data. Round the final values to three significant digits, if necessary. x= 0, 3, 4, 5, 12 Y= 8,2,6,9,12

y hat= 4.88 + 0.525x

Solve the problem.A variable x has a mean, μ, of 10 and a standard deviation, σ, of 7. Determine the standardized version of x.

z= (x-10)/7

The sample mean is a

statistic

The most appropriate graphical display of categorical data is

pie chart

Obtain the linear correlation coefficient for the data. Round your answer to three decimal places. Managers rate employees according to job performance (x) and attitude (y). The results for several randomly selected employees are given below. X: 59, 63, 65, 69, 58, 77, 76, 69, 70, 64, Y:72, 76, 78, 82, 75, 87, 92, 83, 87, 78

r=0.863 (edit-list-stat-linreg(ax+b)

Find the median for the given sample data. The salaries of ten randomly selected doctors are shown below. 150,000 143,000 165,000 238,000 215,000 129,000 139,000 723,000 217,000 166,000

$165,500

Suppose we have 10 exam scores for an introductory statistics course. The scores are 68, 88, 84, 99, 96, 77, 76, 80, 75, 68. One of the intervals of interest is the interval 70 to 90 (where a score of 70 is included in this interval, but 90 is not). Based on the given information, what is the relative frequency for the interval 70 to 90 in this particular class?

.60

Which of the following values of the correlation coefficient indicates the weakest linear relationship between two variables?

0.1 (zero has no linear correlation, 1 has percent postive linear correlation)

For a particular regression analysis, it is found that SST = 900.0 and SSE = 400.00. Calculate the coefficient of determination

0.555 (regression identity theorem SSE=SST-SSR)

Compute the coefficient of determination. Round your answer to four decimal places. A regression equation is obtained for a set of data points. It is found that the total sum of squares is 26.961, the regression sum of squares is 15.044, and the error sum of squares is 11.917.

0.5580 (r^2: coefficient of determination = SSR/SST) (Total sum of squares, SST: the total variation in the observed values of the response variable) (error sum of squares, SSE: the variation in the observed values of the response variable not explained by the regression) (Regression sum of squares, SSR: the variation in the observed values of the response variable explained by the regression)

The average on a exam is 72 with a standard deviation of 6. A student scores a 66 on the exam. Which of the following is correct?

The student's score is 1 standard deviation below the exam average

A graphical display of a data set is given. Identify the overall shape of the distribution as (roughly) bell-shaped, triangular, uniform, reverse J-shaped, J-shaped, right skewed, left skewed, bimodal, or multimodal. A relative frequency histogram for the heights of a sample of adult women is shown below.

bell shaped

You are given information about a straight line. Determine whether the line slopes upward, slopes downward, or is horizontal. The equation of the line is y = 10 - 12x.

slope is downward