Statistics Questions

A student was asked to find a 95 confidence interval for widget width using data from a random sample of size n 29 Which of the following is a correct interpretation of the interval 10 5 p 23 7 Check all that are correct There is a 95 chance that the mean of a sample of 29 widgets will be between 10 5 and 23 7 There is a 95 chance that the mean of the population is between 10 5 and 23 7 With 95 confidence the mean width of all widgets is between 10 5 and 23 7 With 95 confidence the mean width of a randomly selected widget will be between 10 5 and 23 7 The mean width of all widgets is between 10 5 and 23 7 95 of the time We know this is true because the mean of our sample is between 10 5 and 23 7

What changes the width of a confidence interval A marketing director wants a 95 confidence interval for the mean cost of running shoes She randomly samples 40 pairs of shoes and finds that the sample mean was 122 with a sample standard deviation s of 27 The marketing director concluded with 95 confidence that between 113 36 and 130 64 contains the mean cost of all running shoes What would change for a wider confidence interval Select all answers that will make the width wider If the point estimate was larger If the sample size decreased to 30 pairs of shoes If the point estimate was smaller If she increased the confidence level to a 99 confidence level If the sample standard deviation was smaller If she decreased the confidence level to a 90 confidence interval If the sample standard deviation was larger If the sample size increased to 50 pairs of shoes

A confidence interval for the population mean number of jobs a person has before the age of forty was found to be 8 1 to 10 5 Find the midpoint of this confidence interval

All else equal an increase in sample size will cause a n decrease increase O in the size of a confidence interval

Which of the following would result in the widest confidence interval OA sample size of 100 with 95 confidence OA sample size of 30 with 95 confidence OA sample size of 30 with 99 confidence OA sample size of 100 with 99 confidence

If n 41 42 and s 6 construct a confidence interval at a 80 confidence level Give your answers to one decimal place Technolom

In a survey funded by the UW school of medicine 750 of 1000 adult Seattle residents said they did not believe they could come down with a sexually transmitted infection STI Construct a 95 confidence interval estimage of the proportion of adult Seattle residents who don t believe they can contract an STI Use a z score of 1 96 for your computations O 728 772 O 723 777 O 718 782 O 713 878 O 665 835

We wish to estimate what percent of adult residents in a certain county are parents Out of 200 adult residents sampled 130 had kids Based on this construct a 99 confidence interval for the proportion p of adult residents who are parents in this county Give your answers as decimals to three places

A student was asked to find a 95 confidence interval for widget width in mm using data from a random sample of size n 18 Which of the following is a correct interpretation of the interval 14 4 p 21 1 Check all that are correct There is a 95 chance that the mean of a sample of 18 widgets will be between 14 4 mm and 21 1 mm The mean width of all widgets is between 14 4 mm and 21 1 mm 95 of the time We know this is true because the mean of our sample is between 14 4 mm and 21 1 mm With 95 confidence the mean width of a randomly selected widget will be between 14 4 mm and 21 1 mm With 95 confidence the mean width of all widgets is between 14 4 mm and 21 1 mm There is a 95 chance that the mean of the population is between 14 4 mm and 21 1 mm

A random sample of 75 students at the University of Minnesota spend an average of 614 per month in rent with a standard deviation of 219 The distribution is moderately skewed to the high end Which of the following statements are true i 95 of students at the university spend 564 to 664 on rent ii We are 95 confident that the average rent for students at the university is between 564 and 664 iii Because we cannot examine other characteristics of the students in the random sample it is not advisable to construct a confidence interval Oi only O ii only O iii only Oi and ii O i ii and iii

Express the confidence interval 81 4 in interval form Express the answer in decimal format do not enter as percents Question Help Video Post to forum

Calculate x bar for the data shown to two decimal places X 17 2 2 2 7 4 27 1 9 1 14 9 25 5

Express the confidence interval 83 6 6 3 in interval form Express the answer in decimal format do not enter as percents

A student took six exams in a course last semester The scores are shown below 71 87 94 74 94 74 Calculate the mean variance and standard deviation Round to 4 decimal places when needed and use rounded answers for future calculations The mean is The variance is The standard deviation is o

Calculate x bar for the data shown to two decimal places X 18 1 15 1 6 4 10 2 26 6 9 16 7

Determine whether the value 74 4 is a parameter or statistic In a weight loss research study a sample of 130 adults 74 4 lost an average of 10 or more pounds O Parameter O Statistic

Find the width between the interval 5 3

Determine whether the value 41 is a parameter or statistic 41 of a State College A s students are from that state O Parameter O Statistic

Find the width between the interval 10 5

Find the midpoint between the interval 14 16

Find the midpoint between the interval 10 5

Run a regression analysis on the following bivariate set of data with y as the response variable X y 45 4 28 3 38 7 30 4 51 3 26 1 48 2 28 9 47 3 29 2 50 7 28 4 41 7 29 6 51 1 28 9 47 2 28 1 44 2 29 40 9 29 3 42 29 3 Find the correlation coefficient and report it accurate to three decimal places r What proportion of the variation in y can be explained by the variation in the values of x Report answer as a percentage accurate to one decimal place If the answer is 0 84471 then it would be 84 5 you would enter 84 5 without the percent symbol Based on the data calculate the regression line each value to three decimal places y X Predict what value on average for the response variable will be obtained from a value of 39 5 as the explanatory variable Use a significance level of a 0 05 to assess the strength of the linear correlation predicted response value Report answer accurate to one decimal place

1 During his NBA career Larry Bird made approximately 89 of all free throws Suppose Larry makes 10 free throws in a row What is the probability he will make the next free throw a 0 11 b 0 50 c 0 01 d 0 89

Brightness Level x Hours y 10 9 8 7 6 Hours 54 3 2 7 10 20 30 37 39 5 3 30 42 4 1 6 3 6 8 5 9 43 85 55 b Interpret the slope in context 4 5 hours 89 3 2 40 50 60 70 80 90 100 11 Brightness Level 1 a Find the equation for the line of best fit Keep at least 4 decimals for each parameter in the equation I Ashton should expect 0 0439 hours per brightness level Ashton should expect 0 0439 brightness level per hour 92 2 4 c What does the equation predict for the number of hours the phone will last at a brightness lev of 42

Which of the following is false If the correlation between two variables is close to 0 01 then there is a very weak linear relation between them If the correlation coefficient is 1 then the slope must be 1 as well O Correlation coefficient and the slope always have the same sign positive or negative Correlation measures the strength of linear association between two numerical variables

Mountain climbers use a general rule of thumb which estimates that the temperature will drop 3 degrees Fahrenheit for every 1000 ft of elevation The varible T is the temperature and E is the elevation in feet Which of the following best describes the dependent variable in this model Select an answer Which of the following best describes the independent variable in this model Select an answer

A researcher wishes to examine the relationship between years of schooling completed and the number of pregnancies in young women Her research discovers a linear relationship and the least squares line is y 3 2x where x is the number of years of schooling completed and y is the number of pregnancies The slope of the regression line can be interpreted in the following way When amount of schooling increases by one year the number of pregnancies increases by 3 When amount of schooling increases by one year the number of pregnancies decreases by 3 When amount of schooling increases by one year the number of pregnancies decreases by 2 When amount of schooling increases by one year the number of pregnancies increases by 2

Here is a scatter plot for a set of bivariate data What would you estimate the correlation coefficient to be 0 9 0 6 0 0 6 0 9

Please round all answers to 2 decimal places Given the table below use your calculator to find the Line of Best Fit x Y 8 9 1 23 6 7 1 4 7 13 7 1 5 5 7 1 1 8 7 1 15 18 8 7 7

thirty percent of students at a university are business major a random sample of 20 students is selected what is the probability that among the students at least 10 are business major B what is the probability that at least 16 are not business major C what is the probability that exactly 10 are business major D what is the probability that exactly 12are not business majors

Which of the following lines would be the best fit for the data points plotted in the scatter plot below Oy 0 7x 7 2 Oy 7 2x 0 7 Oy 7 2x 0 7 Oy 0 7x 7 2

Use linear regression to find the equation for the line that best fits this data Round both numbers to tw mx b decimal places Write your final answer in a form of an equation y X y 1 2 3 68 83 94 4 112 5 124 6 138

researcher wishes to examine the relationship between years of schooling completed and the number of regnancies in young women Her research discovers a linear relationship and the least squares line is 3 2x where x is the number of years of schooling completed and y is the number of pregnancies The slope of the regression line can be interpreted in the following way When amount of schooling increases by one year the number of pregnancies increases by 3 When amount of schooling increases by one year the number of pregnancies decreases by 3 When amount of schooling increases by one year the number of pregnancies decreases by 2 When amount of schooling increases by one year the number of pregnancies increases by 2

Mountain climbers use a general rule of thumb which estimates that the temperature will drop 3 5 degre Fahrenheit for every 1000 ft of elevation The varible T is the temperature and E is the elevation in feet Which of the following best describes the dependent variable in this model Select an answer Which of the following best describes the independent variable in this model

This bar graph shows the stopping distance in feet for a car traveling at different speeds 800 700 600 500 400 300 200 Distance ft 100 0 40 50 60 70 80 90 100 ft sec ft sec ft sec ft sec ft sec ft sec ft sec Speed Approximately how many feet would it take a car traveling at 60 ft sec to stop feet

Here is a data set summarized as a stem and leaf plot 2 012344467 3 0002255568899999 4 04459 5 225 How many data values are in this data set n What is the minimum value in the last class ans What is the frequency of the class with the most values frequency How many of the original values are greater than 30

Our company s new widget has been growing in sales The histogram below shows sales in millions for the years shown 40 30 20 10 2001 2002 2003 2004 2005 Millions of Widgets Sold In which year did sales first exceed 33 million widgets

Here is a bivariate data set in which you believe y to be the response variable X y 62 8 15 9 38 4 6 1 44 5 27 5 6 17 4 19 4 38 6 34 6 1 9 2 6 29 4 17 9 20 2 2 3 18 9 62 35 6 67 2 30 2 37 3 58 1 63 3 24 3 27 4 40 8 36 2 41 4 Make a scatter plot of this data Which point appears to be an outlier

A regression was run to determine if there is a relationship between hours of TV watched per day x and number of situps a person can do y The results of the regression were y ax b a 1 074 b 25 219 r 0 5329 r 0 73 Use this to predict the number of situps a person who watches 8 hours of TV can do to one decimal place

The table below show data that has been collected from different fields from various farms in a certain valley The table contains the grams of Raspberries tested and the amount of their Vitamin C content in mg Find a linear model that express Vitamin C content as a function of the weight of the Raspberries grams 60 65 70 75 80 85 90 Vitamin C content in mg 14 1 16 6 18 7 20 8 23 2 25 5 27 5 A Find the regression equation y Round your answers to 3 decimal places B Answer the following questions using your un rounded regression equation If we test 120 grams of raspberries what is the expected Vitamin C content mg round to

Let y represent the profit or loss for a certain company years after 1980 Based on the data shown below a statistician calculates a linear model 1 03x 13 16 X 5 6 7 8 9 10 Y 19 55 17 58 22 21 19 84 21 17 25 1 Use the model to estimate the profit in 1990 Round to the nearest cent The estimated profit in 1000

Plot the points in the grid below x axis for the First Quiz y axis for the Second Quiz 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 2 2 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 Clear All Draw Dot

y 20 20 25 30 30 30 30 40 a What is the equation for the line of best fit

Linear Regression Christmas Trees The following table gives the total number of live Christmas trees sold in millions in the United States from 2004 to 2011 Source Statista com 2 0 27 1 4 28 6 t number of years since 2004 C total number of Christmas trees sold in the U S in millions 1 Use the TABLE to determine the number of live Christmas trees sold in the year 2008 In 2008 there were approximately million live Christmas trees sold in the U S 2 Determine the linear regression equation that models the set of data above Use the indicated variables and proper function notation Round to the nearest hundredth as needed C 6 28 2 7 27 30 8 3 Interpret the meaning of the slope of your rounded regression model From 2004 to 2011 the number of Christmas trees sold in the U S increased by approximately trees each year 4 Use the REGRESSION EQUATION to determine the number of live Christmas trees sold in the year 2008 In 2008 there were approximately million live Christmas trees sold in the U S million 5 Your answers to parts 1 and 4 should be different Why is this the case The data are linear The regression equation gives a more precise answer than the value from the table The data are not perfectly linear The regression equation gives only an approximation of the actual value not the exact value The data are not perfectly linear The regression equation gives a more precise answer than the value from the table The data are linear The regression equation gives only an approximation of the actual value not the exact value

The weight of a newborn animal is given by the formula W 6d 4 where W is the weight in grams and d is the number of days since hatching Which variable causes the other variable to change Select an answer Which of the following best describes the dependent variable in this model Select an answer Which of the following best describes the independent variable in this model Select an answer

The TLK cell phone company has a basic cell phone plan This plan includes unlimited talk and text but charges a monthly phone charge fee of 29 00 per month plus 5 50 per 1 GB of data that is used for tha month Write a linear equation that models the monthly cost C of the cell phone based on the number of data GB d used C If your monthly cell phone bill was 36 50 how many GB of data did you use

You are researching the growth of a species of fish You gather a sample of fish and record the age in weeks of each fish and its mass in grams The data is displayed on the grid below with the blue points Age of fish weeks Mass of fish g 4 8 12 16 100 350 350 500 28 36 40 44 350 900 1000 1050 You construct a linear model for the data and your equation is y 21 28x 75 03 where y is the mass in grams of the fish and is the age in weeks a Use the equation to identify the slope of the linear model Use the units for y and a along with the concept of rise over run to interpret the slope in this context b Use the equation to identify the y intercept of the linear model Use the units for y along with the concept that x 0 at the y intercept to interpret the y intercept in this context

vent A Age 12 12 to 15 16 to 24 25 to 64 65 Totals Event B Vaccinated Not Vaccinated 124 873 47 793 946 6 424 266 10 214 213 17 950 590 20 983 450 100 514 773 72 858 178 42 397 381 13 507 909 167 411 883 165 357 696 Totals 47 918 479 16 638 479 38 934 040 173 372 951 55 905 290 332 769 579 Simple Probabilities P Vaccinated P Not Vaccinated P 12 P 12 to 15 P 16 to 24 P 25 to 64 P 65 Joint Probabilities A And B P Vaccinated and 65 P Vaccinated and 12 to 15 P Not Vaccinated and 16 to 24 P Not Vaccinated and 12 Addition Rule A Or B P Vaccinated or 25 P Not Vaccinated or 65 P Vaccinated or 64 P Not Vaccinated or 16 to 24 DINGLY Conditional Probabilities A given B P Vaccinated 12 to 15 P Vaccinated 16 to 24

This morning I stopped at Dunkin Donuts for a coffee They sell coffee in small medium large and extra large There are four kinds of coffee They also offer 7 different kinds of flavor shots How many different ways could I order my coffee ORIGINAL SALTED 11 CARAMEL COCONUT DD Hot CHOCOLATE SALTED CARAME ONDORENG WHITE OD Hot CHOCOLATE 1 Use a table tree diagram or some other strategy to find the total number of ways I could order my coffee Keep in mind that you do not have to add flavor shot Size confee flavor 4 4 8 128

You are performing a two tailed test with test statistic z 2 77 find the p value to 4 decimal places