Statistics - Exam 3
Claim: A minority of adults would erase all of their personal information online if they could. A software firm survey of 496 randomly selected adults showed that 37% of them would erase all of their personal information online if they could. Complete parts (a) and (b) below.
a. p<.50 b. p=.50, p<.50
A presidential candidate plans to begin her campaign by visiting the capitals in 3 of 42 states. What is the probability that she selects the route of three specific capitals?
chegg
Determine whether the underlined number is a statistic or a parameter. 1. a sample of students is selected and it is found that 50% own a vehicle 2. a homeowner measured the voltage supplied on his home of all 365 days of a given year. 3. A particular country has 55total states. If the areas of all55 states are added and the sum is divided by 55, the result is 180,009 square kilometers. 4. The mean salaries for doctors is .....
1. Statistic because the value is a numerical measurement describing a characteristic of a sample. 2. The given value is a parameter for the year because the data collected represent a population. 3. The result is a parameter because it describes some characteristic of a population. 4. The value is a parameter because it is a numerical measurement describing some characteristic of a population
1. the style of shoes of clients are wearing entering a shoe store 2. the postal codes of respondents
1. The data are qualitative because they don't measure or count anything
State whether the data described below are discrete or continuous, and explain why. 1. The volumes of different rooms 2. the exact ages in hours of different cockaroaches found in a certain city 3. the numbers of ingredients in different recipes 4. in an election poll, Joel received 17,575,978 5. area of a park in square feet 6. the number of homework assignments different student turn in for a class 7. the minimum elevations of different elevations 8. number of suitcases on a plane 9. The numbers of hotels in cities 10. the numbers of fingers different people have 11. the weights of acorns that fall off of the tree 12. the # of fish caught in a fishing tourney 13. time for a light bulb to burn out
1. continuous because the data can take on any any value in an interval 2. continuous because the data can take on any value in an interval 3. discrete, because the date can only take on specific values 4. a discrete data set because there are finite number of possible values 5. continuous 6. discrete, because the date can only take on specific values 7. continuous because the data can take on any value in an interval 8. discrete 9. discrete 10. discrete b/c the data can only take on specific values 11. continuous 12. discrete 13. continuous
1. a newspaper asks its readers to call in their opinion 2. a researcher selects every 180th social security number and surveys the corresponding person 3. a woman is selected by a marketing company to participate in a paid focus group. she was randomly selected from a group of women in her tax bracket. 4. To determine her body temperature, Carolyn divides up her day into three parts: morning, afternoon, and evening. She then measures her body temperature at 4 randomly selected times during each part of the day.
1. convenience 2. systematic 3. stratified 4. stratified
1. a researcher plans to obtain data by interviewing siblings of victims who perished in a bombing to see how they're coping now
1. cross-sectional
1. ranks of cars evaluated by a consumers agency 2. political party 3. placements of swimmers in a meet 4. years of elections 5. ratings of novels 6. volumes of planes in cubic meter 7. ages of children 8. acres of land 9. companies that produced movies in 2008 10. stress score where the mean is 0 and the and the increments of measurements are equal.
1. ordinal 2. nominal 3. ordinal 4. interval 5. ordinal 6. ratio 7. ratio 8. nominal 9. nominal 10. interval
Which of the following is NOT a true statement about error in hypothesis testing?
A type I error is making the mistake of rejecting the null hypothesis when it is actually false.
Which of the following is NOT a requirement for testing a claim about a population mean with σ known?
A. The sample mean, x is greater than 30.
Hair Color
Categorical
Identify the type I error and the type II error that correspond to the given hypothesis. The percentage of households with more than 1 pet is less than 65%
Identify the type I error: Reject the null hypothesis that the percentage of households with more than 1 pet is equal to 65% when that percentage is actually equal to 65%. Identify the type II error: Fail to reject the null hypothesis that the percentage of households with more than 1 pet is equal to 65% when that percentage is actually less than 65%.
Assume that the sample is a simple random sample obtained from a normally distributed population of IQ scores of statistics professors. Use the table below to find the minimum sample size needed to be 99% confident that the sample standard deviation s is within 50% of σ. Is this sample size practical?
Is this sample size practical? Yes, because the sample size is small enough to be practical for most applications.
Eight different senators from the current U.S. Congress are randomly selected without replacement and whether or not they've served over 2 terms is recorded.
No, because the trials of the experiment are not independent and the probability of success differs from trial to trial. Your answer is correct.
Six hundred different voters in a region with two major politicalparties, A andB, are randomly selected from the population of 3500 registered voters. Each is asked if he or she is a member of political partyA, recording Yes or No.
No, the trials are not independent and the samples are more than 5% of the population
The statistics of n=22 and s=14.3 result in this 95% confidence interval estimate of σ: 11.0<σ<20.4. That confidence interval can also be expressed as (11.0, 20.4). Given that 15.7±4.7 results in values of 11.0 and 20.4, can the confidence interval be expressed as 15.7±4.7 as well?
No. The format implies that s=15.7, but s is given as 14.3. In general, a confidence interval for σ does not have s at the center.
Park officials make predictions of times to the next eruption of a particular geyser, and collect data for the errors (minutes) in those predictions. The display from technology available below results from using the prediction errors to test the claim that the mean prediction error is equal to zero. Comment on the accuracy of the predictions. Use a 0.05 significance level. Identify the null and alternative hypotheses, test statistic, P-value, and state the final conclusion that addresses the original claim.
State the final conclusion that addresses the original claim. reject, sufficient, is not, some error
Which of the following is NOT a property of the chi-square distribution?
The mean of the chi-square distribution is 0.
Which of the following is NOT a requirement for testing a claim about a standard deviation or variance?
The population must be skewed to the right.
Which of the following is not a requirement for testing a claim about a population with σ not known?
The population mean, μ, is equal to 1.
A research center poll showed that 75% of people believe that it is morally wrong to not report all income on tax returns. What is the probability that someone does not have this belief?
The probability that someone does not believe that it is morally wrong to not report all income on tax returns is . 25
In the largest clinical trial ever conducted, 401,974 children were randomly assigned to two groups. The treatment group consisted of 201,229 children given the Salk vaccine for polio, and the other 200,745 children were given a placebo. Among those in the treatment group, 33 developed polio, and among those in the placebo group, 115 developed polio. If we want to use the methods for testing a claim about two population proportions to test the claim that the rate of polio is less for children given the Salk vaccine, are the requirements for a hypothesis test satisfied? Explain.
The requirements are satisfied; the samples are simple random samples that are independent, and for each of the two groups, the number of successes is at least 5 and the number of failures is at least 5.
A data set includes the height of of 130 college students and 130 teachers
The samples are independent because there is not a natural pairing between the two samples.
Among the 500 respondents, 11% chose chocolate pie, and the margin of error was given as ±4 percentage points. Describe what is meant by the statement that "the margin of error was given as ±4 percentage points."
The statement indicates that the interval 11%±4% is likely to contain the true population percentage of people that prefer chocolate pie.
Identify the type I error and the type II error that corresponds to the given hypothesis. The proportion of people who write with their left hand is equal to 0.16.
Which of the following is a type I error? Reject the claim that the proportion of people who write with their left hand is 0.16 when the proportion is actually 0.16. Which of the following is a type II error? Fail to reject the claim that the proportion of people who write with their left hand is 0.16 when the proportion is actually different from 0.16.
A bottle contains a label stating that it contains pills with 500 mg of vitamin C, and another bottle contains a label stating that it contains pills with 325 mg of aspirin. When testing claims about the mean contents of the pills, which would have more serious implications: rejection of the vitamin C claim or rejection of the aspirin claim? Considering only a type I error and using the same sample size, is it wise to use the same significance level for hypothesis tests about the mean amount of vitamin C and the mean amount of aspirin?
aspirin, aspirin, vitamin C, smaller
Assume that a simple random sample has been selected from a normally distributed population and test the given claim. Identify the null and alternative hypotheses, test statistic, P-value, and state the final conclusion that addresses the original claim. A safety administration conducted crash tests of child booster seats for cars. Listed below are results from those tests, with the measurements given in hic (standard head injury condition units). The safety requirement is that the hic measurement should be less than 1000 hic. Use a 0.05 significance level to test the claim that the sample is from a population with a mean less than 1000 hic. Do the results suggest that all of the child booster seats meet the specified requirement? 641 577 1078 575 545 544
t=-4.008, p=.005 There is strong evidence that the mean is less than 1000 hic, but one of the booster seats has a measurement that is greater than 1000 hic.
