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jessie gom

jessie g.

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Vivek Kumar verified

Numerade educator

In a survey, 23 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $46 and standard deviation of $5. Construct a confidence interval at a 98% confidence level.

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23) If n=200 and ^ (p-hat) = 0.18, construct a 90% confidence interval. As in the reading, in your calculations:--Use z = 1.645 for a 90% confidence interval--Use z = 2 for a 95% confidence interval--Use z = 2.576 for a 99% confidence interval.Give your answers to three decimals 24) Out of 100 people sampled, 47 had kids. Based on this, construct a 95% confidence interval for the true population proportion of people with kids. As in the reading, in your calculations:--Use z = 1.645 for a 90% confidence interval--Use z = 2 for a 95% confidence interval--Use z = 2.576 for a 99% confidence interval.Give your answers to three decimals

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21) If n=210 and ˆpp^ (p-hat) =0.73, find the margin of error at a 99% confidence level.As in the reading, in your calculations:--Use z = 1.645 for a 90% confidence interval--Use z = 2 for a 95% confidence interval--Use z = 2.576 for a 99% confidence interval.22) recent poll, 470 people were asked if they liked skiing, and 45% said they did. Find the margin of error of this poll, at the 95% confidence level.As in the reading, in your calculations:--Use z = 1.645 for a 90% confidence interval--Use z = 2 for a 95% confidence interval--Use z = 2.576 for a 99% confidence interval.

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20) A student was asked to find a 95% confidence interval for the proportion of students who take notes using data from a random sample of size n = 85. Which of the following is a correct interpretation of the interval 0.1 < p < 0.32?Check all that are correct.A.There is a 95% chance that the true proportion of notetakers in a sample of 85 students will be between 0.1 and 0.32.B.With 95% confidence, the true proportion of all students who take notes is between 0.1 and 0.32.C.The proportion of all students who take notes is between 0.1 and 0.32, 95% of the time.D.We are 95% confident that the proportion of the population can be a number between 0.1 and 0.32.E.With 95% confidence, a randomly selected student takes notes in a proportion of their classes that is between 0.1 and 0.32.

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19b)In a survey, 800 adults in a certain country were asked how many hours they worked in the previous week. Based on the results, a 95% confidence interval for mean number of hours worked was lower bound: 39 hours and upper bound: 48 hours. Interpretation #3: We are 95% confident that the mean number of hours worked by adults in this country in the previous week was between 39 hours and 48 hours.Flawed. This interpretation implies that the population mean varies rather than the interval.Flawed. This interpretation makes an implication about individuals rather than the mean.Flawed. This interpretation does not make it clear that the 95% is the probability that the mean is within the interval.This is a reasonable interpretationInterpretation #4: 95% of adults in this country worked between 39 hours and 48 hours last week.Flawed. This interpretation implies that the mean is only for last week.Flawed. This interpretation makes an implication about individuals rather than the mean.Flawed. This interpretation does not make it clear that the 95% is the probability that the mean is within the interval.This is a reasonable interpretation

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19) In a survey, 800 adults in a certain country were asked how many hours they worked in the previous week. Based on the results, a 95% confidence interval for mean number of hours worked was lower bound: 39 hours and upper bound: 48 hours. Which of the following represents a reasonable interpretation of the result? For those that are not reasonable, explain the flaw. Interpretation #1: There is a 95% chance the mean number of hours worked by adults in this country in the previous week was between 39 hours and 48 hours.Flawed. This interpretation makes an implication about individuals rather than the mean.Flawed. This interpretation implies that the population mean varies rather than the interval.Flawed. This interpretation implies that the mean is only for last week.This is a reasonable interpretationInterpretation #2: We are 95% confident that the mean number of hours worked by adults in a particular area of this country in the previous week was between 39 hours and 48 hours.Flawed. This interpretation implies that the population mean varies rather than the interval.Flawed; the interpretation should be about the mean number of hours worked by adults in the whole country, not about adults in the particular area.Flawed. This interpretation makes an implication about individuals rather than the mean.This is a reasonable interpretation

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16)You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately ? = 61.3 ? = 61.3 . You would like to be 95% confident that your estimate is within 2 of the true population mean. How large of a sample size is required? Answer is not 3757.7…18) A student was asked to find a 95% confidence interval for widget width using data from a random sample of size n = 27. Which of the following is a correct interpretation of the interval 13.6 < ? < 27?Check all that are correct.A.The mean width of all widgets is between 13.6 and 27, 95% of the time. We know this is true because the mean of our sample is between 13.6 and 27.B.With 95% confidence, we can say that the mean of the population is anywhere between 13.6 and 27.C.We are 95% confident that the true mean width of all widgets is between 13.6 and 27.D.With 95% confidence, the mean width of a randomly selected widget will be between 13.6 and 27.E.There is a 95% chance that the mean of a sample of 27 widgets will be between 13.6 and 27.

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ANSWERED

Katy Gimbel verified

Numerade educator

16)You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately ? = 61.3 ? = 61.3 . You would like to be 95% confident that your estimate is within 2 of the true population mean. How large of a sample size is required? 17) You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately ? = 60.3 ? = 60.3 . You would like to be 99% confident that your estimate is within 0.1 of the true population mean. How large of a sample size is required? As in the reading, in your calculations: --Use z = 1.645 for a 90% confidence interval --Use z = 2 for a 95% confidence interval --Use z = 2.576 for a 99% confidence interval.

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