Statistics Questions

6 Dr Hafen is doing research on the effects of study time how many minutes students study on test performance their score on an exam He hypothesizes that the amount of study time will impact an individual s performance on the exam Then Dr Hafen collects data on 100 students and runs a Pearson correlation a In your own words please describe Dr Hafen s Null Hypothesis b If Dr Hafen makes a Type I error what would that mean in the context of the study c If Dr Hafen makes a Type II error what would that mean in the context of the study

2 Previously an organization reported that teenagers spent 4 5 hours per week on average on the phone The organization thinks that currently the mean is higher Fifteen randomly chosen teenagers were asked how many hours per week they spend on the phone The sample mean was 4 75 hours with a sample standard deviation of 2 0 Give the null and alternative hypotheses Do not run a test

7 Why are both sample size N and effect size e g r important when conducting a hypothesis test

9 Please draw a scatterplot that shows a relatively strong association and one that shows a relatively weak association Be sure to label them well

onstruct a boxplot for the given data Include values of the 5 number summary in all boxplots 6 The test scores of 32 students are listed below Construct a boxplot for the data set 32 37 41 44 46 48 53 55 57 57 59 63 65 66 68 69 70 71 74 74 75 77 78 79 81 82 83 86 89 92 95 99

2 If we know that population mean is 17 population standard deviation is 4 5 conduct a two tailed z test to determine if the following data set allows us to reject the null hypothesis 14 14 20 14 13 10 10 8 10 12

Find the percentile for the data value 14 Data set 55 38 30 66 67 68 44 Data value 55 Find the indicated measure 15 Use the given sample data to findQ3 49 52 52 52 71 71 67 67 55 55

Determine which score corresponds to the higher relative position 13 Which is better a score of 92 on a test with a mean of 71 and a standard deviation of 15 or a score of 688 on a test with a mean of 493 and a standard deviation of 150

Solve the problem Round results to the nearest hundredth 10 The mean of a set of data is 5 73 and its standard deviation is 3 44 Find the z score for a value of 13 87

Find the number of standard deviations from the mean Round your answer to two decimal places 11 The annual snowfall in a town has a mean of 38 inches and a standard deviation of 10 inches Last year there were 63 inches of snow How many standard deviations from the mean is that

Use the empirical rule to solve the problem 8 At one college GPA s are normally distributed with a mean of 2 9 and a standard deviation of 0 6 What percentage o students at the college have a GPA between 2 3 and 3 5

9 The coefficient of variation expressed as a percent is used to describe the standard deviation relative to the mean allows us to compare variability of data sets with different measurement units and is calculated as follows Coefficient of variation 100 s x Find the coefficient of variation for the following sample of weights in pounds 130 153 127 172 I 186 150 105 116 197 125

5 List the following correlations from weakest to strongest d 22 a 33 b 74 c 81

4 Why do we say that correlation does not equal causation Please give an example

1 Calculate the correlation coefficient for the relationship of interval variables X and Y in DATA SET A Make sure you show all of your work and demonstrate the use of the formulas DATA SET A X 8 15 6 5 10 15 Y 5 11 10 10 6 11 File Preview

Assume a population of 40 46 49 and 54 Assume that samples of size n 2 are randomly selected with replacement from the population Listed below are the sixteen different samples Complete parts a through c 40 40 40 46 40 49 49 40 49 46 49 49 46 1 16 1 8 51 5 40 54 49 54 54 1 46 40 54 40 46 46 54 46 1 47 16 Type integers or simplified fractions Use ascending order of the sample medians b Compare the population median to the mean of the sample medians Choose the correct answer below 46 49 54 49 OA The population median is not equal to the mean of the sample medians it is also not half or double the mean of the sample medians OB The population median is equal to half of the mean of the sample medians OC The population median is equal to double the mean of the sample medians 46 54 54 54 D

5 Michael gets test grades of 73 77 82 and 86 He gets a 93 on her final exam Find the weighted mean if the tests each count for 15 and the final exam counts for 40 of the final grade Round to one decimal place Percentage Grades

Find the standard deviation and variance for the given data Round your answer to one more decimal place than th original data 6 18 20 18 27 x xbar wwww x xbar 2

Points 0 87 of 1 Three randomly selected children are surveyed The ages of the children are 1 3 and 8 Assume that samples of size n 2 are randomly selected with replacement from the population of 1 3 and 8 Listed below are the nine different samples Complete parts a through d 1 1 1 3 1 8 3 1 3 3 3 8 8 1 8 3 8 8 8 Type integers or simplified fractions c Find the mean of the sampling distribution of the sample median 4 Type an integer or a decimal Do not round d Based on the preceding results is the sample median an unbiased estimator of the population median Why or why not points O A The sample median does not target the population median As such the sample median does not make a good estimator of the population median OB The sample median targets the population median As such the sample median does not make a good estimator of the population median OC The sample median targets the population median As such the sample median makes a good estimator of the population median OD The sample median does not target the population median As such the sample median makes a good estimator of the population median Save

The accompanying table desc Complete parts a through d BEB Click the icon to view the a Find the probability of gettin Type an integer or a deci b Find the probability of gettin Type an integer or a deci Which probability is relevan Number of Girls x 0 1 2 2 5 3 4 RM 5 2 6 7 8 P x 0 003 0 034 0 107 0 194 0 199 0 324 0 194 0 107 0 034 0 003 The random variable x represents the number of girls among 8 children 8 births the result from part a or part b

Based on a survey assume that 48 of consumers are comfortable having drones deliver their purchases Suppose we want to find the probability that when four consumers are randomly selected exactly two of them are comfortable with the drones What is wrong with using the multiplication rule to find the probability of getting two consumers comfortable with drones followed by two consumers not comfortable as in this calculation 0 48 0 48 0 52 0 52 0 0623 Choose the correct answer below OA The probability of the second consumer being comfortable with drones cannot be treated as being independent of the probability of the first consumer being comfortable with drones OB There are other arrangements consisting of two consumers who are comfortable and two who are not The probabilities corresponding to those other arrangements should also be included in the result OC The event that a consumer is comfortable with drones is not mutually exclusive with the event that a consumer is not comfortable with drones OD The calculation assumes that the first two consumers are comfortable with drones and the last two are not but this arrangement is not possible

V x 2 3y x 0 y 9 Sketch the region y 10 O 8 6 4 2 y 10 8 6 4 the solid obtained by rotating the region bounded by the giver curves about the specified me about the y axis 2 2 4 6 F 8 10 X X 10 8 6 y 4 2 y 10 8 6 4 2 2 4 i1 6 8 10 X X 91 F Mostly sunny

the random variable X is normally distributed with mean 50 and standard dev Compute the probability Be sure to draw a normal curve with the area correspondi ability shaded P 57 x 68 AAA 50 57 68 50 57 68 x 68 Round to four decimal places as needed G 50 57 68

The mean incubation time of fertilized eggs is 19 days Suppose the incubation approximately normally distributed with a standard deviation of 1 day a Determine the 15th percentile for incubation times b Determine the incubation times that make up the middle 39 of fertilized en

s Complete parts a and b below than days is vide a second interpretation of the area using the given values Select the correct choice ow and fill in the answer boxes to complete your choice De integers or decimals A The probability that a randomly selected human pregnancy lasts more than B The probability that a randomly selected human pregnancy lasts less than days is days is

the monthly charges for cell phone plans are normally distributed with mean u deviation a 20 a normal curve with the parameters labeled e the region that represents the proportion of plans that charge less than 48 ose the area under the normal curve to the left of X 48 is 0 1587 Provide an ation of this result et the correct choice below and fill in the answer box to complete your choice whole number The probability is 0 1587 that a randomly selected cell phone plan in this populatie ess than per month The probability more than is 0 1587 that a randomly selected cell phone plan in this populatic per month

dard normal curve in parts a through c below a Find the area under the normal curve to the left of z 3 plus the area under the now urve to the right of z 3 he combined area is Round to four decimal places as needed

Determine the value of z such that the area to the right of z is 0 8508 Round the solution to two decimal places as z values are traditionally rounded

7 Find the 81st percentile 81st percentile is und to two decimal places as needed

Find the area under the standard normal curve between z 0 83 and z 3 21 Round the solution to four decimal places if necessary Area

standard normal distribution 85 of the distribution from the area in the The z scores are Use a comma to separate answers as needed Round to two decimal places as neede

me approximate z score that corresponds to a right tail area of 0 15 is Round to two decimal places as needed

andard deviation o 20 Draw a normal curve with the parameters labeled Shade the region that represents the proportion of plans that charge less than 48 Suppose the area under the normal curve to the left of X 48 is 0 1587 Provide an terpretation of this result A 48 68 88 108 OB 28 48 68 O C 48 28 68 108 O D 48 68 8

is the z score such that the area under the curve to the left is 0 93 Round to two decimal places as needed

ally distributed with mean 50 and standard devi 7 Compute the probability Be sure to draw a normal curve with the area corresponding obability shaded P 57 x 68 A 50 57 00 Q Q B Q O C

The graph of a normal curve is given Use the graph to identify the value of and o The value of is 5 The value of o is 55 40 25 10 5 20 35 50 X 65

standard deviation o 500 grams Complete parts a through c below a Draw a normal curve with the parameters labeled Choose the correct graph below O A 2400 2900 3400 OB 1 2900 3400 3900 O C 3400 3900 4400 O D 2400 3

graph of a normal curve is given the graph to identify the value of alue of u is 55 40 25 10 5 20 35 50

plete the statement below The points at x t are the two points and x The points are x o and x o 3 The points are x 30 and x 3o C The points are x 20 and x 2o are the inflection points on th

Over the past few decades public health officials have examined the link between weight concerns and teen girls smoking Researchers surveyed a group of 273 randomly selected teen girls living in Massachusetts between 12 and 15 years old After four years the girls were surveyed again Sixty three said they smoked to stay thin Is there good evidence that more than thirty percent of the teen girls smoke to stay thin Give the null and alternative hypotheses Do not run a test

Previously 4 of mothers smoked more than 21 cigarettes during their pregnancy An obstetrician believes that the percentage of mothers who smoke 21 cigarettes or more is today She randomly selects 120 pregnant mothers and finds that 2 of them smoked more cigarettes during pregnancy Test the researcher s statement at the a 0 05 level c gnificance hat are the null and alternative hypotheses versus H pe integers or decimals Do not round Cause npo 1 Po P value und to one decimal place as needed 10 the normal model be used to approximate

r the mean age of an inmate on death row was 39 9 years A sociologist wonder the mean age of a death row inmate has changed since then She randomly sel w inmates and finds that their mean age is 38 2 with a standard deviation of 8 9 ct a 95 confidence interval about the mean age What does the interval imply k the icon to view the table of critical t values egers or decimals Do not round Ea 95 confidence interval about the mean age confidence the mean age of a death row inmate is between two decimal places as needed years and ye

mothers smoked more than 21 cigarettes during their pregnancy Ar obstetrician believes that the percentage of mothers who smoke 21 cigarettes or more 4 today She randomly selects 120 pregnant mothers and finds that 2 of them smoke more cigarettes during pregnancy Test the researcher s statement at the a 0 05 leve significance une revalo Round to one decimal place as needed Find the P value P value Round to three decimal places as needed Is there sufficient evidence to support the obstetrician s statement

urce A stock analyst believes that the stock volume in 2018 is different from ed on a random sample of 30 trading days in 2018 he finds the sample mean in shares with a standard deviation of s 11 7 million shares Test the hypoth ng a 95 confidence interval Complete parts a through c below uct a 95 confidence interval about the sample mean of stocks traded in 201 confidence the mean stock volume in 2018 is between million shares and ares three decimal places as needed

standard deviation in the pressure required to open a certain valve is known to be a to changes in the manufacturing process the quality control manager feels that the pr ability has been reduced State the null and alternative hypotheses in words State the null and alternative hypotheses symbolically Explain what it would mean to make a Type I error Explain what it would mean to make a Type II error What would it mean to make a Type I error the hypothesis that the pressure variability is e manager when the true pressure variability is pe integers or decimals Do not round ld it mean to make a Tvne Il error psi

ly 4 of mothers smoked more than 21 cigarettes during their pregnancy Ar ian believes that the percentage of mothers who smoke 21 cigarettes or more y She randomly selects 120 pregnant mothers and finds that 2 of them smok arettes during pregnancy Test the researcher s statement at the 0 05 leve nce sufficient evidence to support the obstetrician s statement No reject the null hypothesis because the P value is less than a There is not evidence to conclude that the percentage of mothers who smoke 21 or more during pregnancy is less than 4 No do not reject the null hypothesis because the P value is greater than a TB sufficient evidence to conclude that the percentage of mothers who smoke 21 cigarettes during pregnancy is less than 4

ar the mean age of an inmate on death row was 39 9 years A sociologist wond the mean age of a death row inmate has changed since then She randomly s w inmates and finds that their mean age is 38 2 with a standard deviation of 8 ct a 95 confidence interval about the mean age What does the interval imply k the icon to view the table of critical t values ince the mean age from the earlier year is not contained in the interval there is ufficient evidence to conclude that the mean age had changed ince the mean age from the earlier year is not contained in the interval there is ufficient evidence to conclude that the mean age had changed nce the mean age from the earlier year is contained in the interval there is not fficient evidence to conclude that the mean age had changed nce the mean age from the earlier year is contained in the interval there is suf idence to conclude that the mean age had changed

me year the mean age of an inmate on death row was 39 9 years A sociologist w mether the mean age of a death row inmate has changed since then She random eath row inmates and finds that their mean age is 38 2 with a standard deviation Onstruct a 95 confidence interval about the mean age What does the interval in Click the icon to view the table of critical t values hoose the correct hypotheses ype integers or decimals Do not round 05

devi on in the pressure required to open a certain valve is known to be to changes in the manufacturing process the quality control manager feels that the bility has been reduced ate the null and alternative hypotheses in words tate the null and alternative hypotheses symbolically explain what it would mean to make a Type I error explain what it would mean to make a Type Il error ate the hypotheses symbolically psi psi integers or decimals Do not round

ard deviation in the pressure required to open a certain valve is known to be a anges in the manufacturing process the quality control manager feels that the has been reduced he null and alternative hypotheses in words he null and alternative hypotheses symbolically what it would mean to make a Type I error n what it would mean to make a Type II error e standard deviation in the pressure required to open a certain valve is 0 9 psi e standard deviation in the pressure required to open a certain valve is different 9 psi e standard deviation in the pressure required to open a certain valve is less than 1