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Select the most appropriate response.
The purpose of statistical inference is to provide information about the
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sample based upon information obtained from the population population based upon information obtained from a sample on
Determine the point estimate.
A survey of 400 non-fatal accidents showed that 189 involved the use
of a cell phone. Determine a point estimate for p, the population
proportion of non-fatal accidents that involved the use of a cell phone.
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on Construct the requested confidence interval. A media poll of 500 air travelers surveyed in national airports found that 370 favor tighter security procedures in boarding planes. Construct a 90% confidence interval for the proportion of all air travelers who are in favor of tighter security procedures.
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St. Petersburg College | STA 2023 – ELEMENTARY
STATISTICS | Module 4 Test | 2025-
on
Determine the margin of error.
It has been determined with 95% confidence that the proportion of on-
line students at SPC who live in Pinellas County is between 0.73 and
Determine the margin of error associated with this confidence interval.
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on
Determine the sample proportion.
It has been determined with 95% confidence that the proportion of on-
line students at SPC who live in Pinellas County is between 0.73 and
Determine the sample proportion of on-line SPC students who live in
Pinellas County.
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on
Construct the requested confidence interval.
A survey of 300 union members in New York State reveals that 112
favor the Republican candidate for governor. Construct a 90%
confidence interval for the percentage of all New York State union
members who favor the Republican candidate.
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on
Determine the necessary sample size.
What is the approximate sample size required to estimate the
percentage of Americans who have earned a college degree to within
2%, with 95% confidence?
Recall: the worst case scenario would assume that p = 0.
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on
Select the most appropriate response.
What will happen (other things being equal) if you decrease the
confidence level for a given confidence interval?
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It will be narrower It will be wider It will not change on Determine the margin of error. In a survey of 500 residents, 300 were opposed to the use of photo-cops for issuing traffic tickets. Find the margin of error that corresponds to a 95% confidence interval for the proportion of residents that are opposed to the use of photo-cops for issuing traffic tickets.
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on
Select the most appropriate response.
What will happen (other things being equal) if you increase the sample size used to construct a given confidence interval?
on Determine the width of the given confidence interval. An environmental journal discussing current water usage within the US reports, with 95% confidence, the average number of household gallons used per person per day is between 82 and 88. The study was based on a random sample of 30 individuals throughout the nation.
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on Select the most appropriate response. An article in an educational journal discussing a non-conventional high school reading program reports, with 95% confidence, the average score on the reading portion of the SAT is between 520 and 560. The study was based on a random sample of 20 students and it was assumed that SAT scores would be approximately normally distributed. Determine the average SAT reading score of the 20 students sampled.
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on
Construct the requested confidence interval.
In a recent study of 42 eighth graders, the mean number of hours per
week that they watched television was 19.6 with a standard deviation
of 5.8 hours. Construct a 98% confidence interval for the population
mean.
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on
Interpret the confidence interval.
An experiment was conducted to estimate the average fat content of a
quarter pounder with cheese. A random sample of 30 burgers
produced a sample mean of 26 grams which resulted in a 95%
confidence interval of ( 25 , 27) grams.
Which of the following is the correct interpretation of this interval?
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95% of the quarter pounders with cheese sampled had a fat content between 25 and 27 grams.
on
Select the most appropriate response.
Data collected by child development scientists produced the following 90% confidence interval for the average age (in months) at which children say their first word: 10.4 < μ < 13.8. In this example, what does the phrase 90% confident mean?
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There is a 90% chance that the sample mean is between 10.4 and 13.8 months. If many samples are drawn, the computed confidence intervals will contain the population mean approximately 90% of the time. There is a 90% chance that the population mean is between 10.4 and 13.8 months. If many samples are drawn, the population mean will be between 10.4 and 13.8 months approximately 90% of the time. on
Select the most appropriate response.
Which of the following is a benefit of increasing the sample size when trying to estimate the mean from a sample average?
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A reduction in the bias of the estimate. A reduction in the variability of the estimate. An increase in the width of the resulting confidence interval. There will be no benefit because the population has not changed. on
Construct the requested confidence interval. An electronics company just finished designing a new tablet computer and is interested in estimating its battery-life. A random sample of 20 laptops with a full charge was tested and the battery-life was found to be approximately normal with a mean of 6 hours and a sample standard deviation of 1.5 hours. Which of the following is the correct form for a 99% confidence interval?
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CI.99(μ)=6±2.576(0.3354) CI.99(μ)=6±2.576(1.5) CI.99(μ)=6±2.861(0.3354) CI.99(μ)=6±2.861(1.5) on Evaluate the claim. A weight-loss program claims that, on average, participants lose 10 pounds during the first month of participation. An independent organization constructed a 95% confidence interval of (6.63 , 9.15) for the average amount of weight lost during the first month of this program. What conclusion best evaluates the claim made about this program’s effectiveness?
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With 95% certainty, the claim of losing 10 pounds on average during the first month of participation is false. With 95% certainty, the claim of losing 10 pounds on average during the first month of participation is correct. With 100% certainty, the claim of losing 10 pounds on average during the first month of participation is false. With 100% certainty, the claim of losing 10 pounds on average during the first month of participation is correct. on Evaluate the claim. An insurance company reported that, on average, claims for a certain medical procedure are $942. An independent organization constructed a 95% confidence interval of ($930 , $950) for the average amount claimed for the particular medical
