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Here are summary statistics for randomly selected weights of newborn girls: n=36, x̅= 3216.7g, s=688.5g. Use a confidence level of 99%
Identify the critical value tα/2
2.72
It can be said with 90% confidence that the sample mean age of movie patrons is within 3 years of the population mean. Assume that σ = 19.7 years, based on a previous report.
What is the Sample Size
117
In a poll of 512 human resource professionals, 45.5% said that body piercings and tattoos were big personal grooming red flags.
Among the human resource professionals who were surveyed, how many of them said that body piercings and tattoos were big personal grooming red flags?
233
Find the sample size needed to estimate the percentage of adults who can wiggle their ears. Use a margin of error of 3 percentage points and use a confidence level of 95%.
Assume that p and q are unknown.
1068
In a study of cell phone use and brain hemispheric dominance, an Internet survey was e-mailed to 2576 subjects randomly selected from an online group involved with ears. 935 surveys were returned. Construct a 99% confidence interval for the proportion of returned surveys.
Find the best point estimate of the population proportion (p).
0.363
Here are summary statistics for randomly selected weights of newborn girls: n=36, x̅= 3216.7g, s=688.5g. Use a confidence level of 99% and critical value of 2.72.
Find the margin of error.
312
It can be said with 90% confidence that the sample mean age of movie patrons is within 3 years of the population mean. Assume that σ = 19.7 years, based on a previous report. Sample size 117.
Should the sample be obtained from one movie at one theater?
The sample should not be obtained from one movie at one theater, because that sample could be easily biased. Instead, cluster sample of the broader population should be obtained.
The sample should be obtained from one movie at one theater, because that sample is representative of the population.
The sample should not be obtained from one movie at one theater, because that sample could be easily biased. Instead, a stratified sample of the broader population should be obtained.
The sample should not be obtained from one movie at one theater, because that sample could be easily biased. Instead, a simple random sample of the broader population should be obtained.
4. The sample should not be obtained from one movie at one theater, because that sample could be easily biased. Instead, a simple random sample of the broader population should be obtained.
In a poll of 512 human resource professionals, 45.5% said that body piercings and tattoos were big personal grooming red flags. Among the human resource professionals who were surveyed, 233 said that body piercings and tattoos were big personal grooming red flags.
Construct a 99% confidence interval estimate of the proportion of all human resource professionals believing that body piercings and tattoos are big personal grooming red flags.
0.398< p<0.512
Find the sample size needed to estimate the percentage of adults who can wiggle their ears. Use a margin of error of 3 percentage points and use a confidence level of 95%.
Assume that 23% of adults can wiggle their ears
756
In a study of cell phone use and brain hemispheric dominance, an Internet survey was e-mailed to 2576 subjects randomly selected from an online group involved with ears. 935 surveys were returned. Construct a 99% confidence interval for the proportion of returned surveys. Point Estimate of 0.363.
Identify the value of the margin of error
0.024
Here are summary statistics for randomly selected weights of newborn girls: n=36, x̅= 3216.7g, s=688.5g. Use a confidence level of 99%, critical value of 2.72, and it is within 312.
Find the confidence interval estimate of μ.
2904.1< μ<3529.3
In a test of the effectiveness of garlic for lowering cholesterol, 50 subjects were treated with garlic in a processed tablet form. Cholesterol levels were measured before and after the treatment. The changes (before - after) in their levels of LDL cholesterol (in mg/dL) have a mean of 3.2 and a standard deviation of 18.7.
What is the 95% confidence interval estimate of the population mean μ?
-2.11< μ< 8.51
In a poll of 512 human resource professionals, 45.5% said that body piercings and tattoos were big personal grooming red flags. Among the human resource professionals who were surveyed, 233 of them said that body piercings and tattoos were big personal grooming red flags. The 99% confidence interval estimate of the proportion is 0.398< p<0.512
Now, determine the confidence interval with a confidence level of 80%.
0.427< p<0.483
An IQ test is designed so that the mean is 100 and the standard deviation is 12 for the population of normal adults. It can be said with 99% confidence that the sample mean is within 3 IQ points of the true mean. Assume that σ = 12.
What is the Sample Size?
107
In a study of cell phone use and brain hemispheric dominance, an Internet survey was e-mailed to 2576 subjects randomly selected from an online group involved with ears. 935 surveys were returned. Construct a 99% confidence interval for the proportion of returned surveys. Point estimate of 0.363 and the percentage is no more than 0.024.
A. Construct the 99% confident interval.
B. Write a statement that correctly interprets the confidence interval. Choose the correct answer below.
One has 99% confidence that the interval from the lower bound to the upper bound actually does contain the true value of the population
99% of sample proportions will fall between the lower bound and the upper bound.
There is a 99% chance that the true value of the population proportion will fall between the lower bound and the upper bound.
One has 99% confidence that the sample proportion is equal to the population proportion.
A) 0.339< p<0.387
B) 1. One has 99% confidence that the interval from the lower bound to the upper bound actually does contain the true value of the population
Here are summary statistics for randomly selected weights of newborn girls: n=36, x̅= 3216.7g, s=688.5g. Use a confidence level of 99%, critical value of 2.72, margin of error of 312, and confidence interval of 2904.1< μ<3529.3
Write a brief statement that interprets the confidence interval. Choose the correct answer below.
Approximately 99% of sample mean weights of newborn girls will fall between the lower bound and the upper bound.
One has 99% confidence that the interval from the lower bound to the upper bound contains the true value of the population mean weight of newborn girls.
One has 99% confidence that the sample mean weight of newborn girls is equal to the population mean weight of newborn girls.
There is a 99% chance that the true value of the population mean weight of newborn girls will fall between the lower bound and the upper boundary.
2. One has 99% confidence that the interval from the lower bound to the upper bound contains the true value of the population mean weight of newborn girls.
In a test of the effectiveness of garlic for lowering cholesterol, 50 subjects were treated with garlic in a processed tablet form. Cholesterol levels were measured before and after the treatment. The changes (before - after) in their levels of LDL cholesterol (in mg/dL) have a mean of 3.2 and a standard deviation of 18.7. 95% confidence interval estimate of the mean net change in LDL cholesterol after the garlic treatment.
CL: -2.11< μ< 8.51
What does the confidence interval suggest about the effectiveness of the treatment?
The confidence interval limits do not contain 0, suggesting that the garlic treatment did not affect the LDL cholesterol levels.
The confidence interval limits do not contain 0, suggesting that the garlic treatment did affect the LDL cholesterol levels.
The confidence interval limits contain 0, suggesting that the garlic treatment did affect the LDL cholesterol levels.
The confidence interval limits contain 0, suggesting that the garlic treatment did not affect the LDL cholesterol levels
4. The confidence interval limits contain 0, suggesting that the garlic treatment did notaffect the LDL cholesterol levels
In a poll of 512 human resource professionals, 45.5% said that body piercings and tattoos were big personal grooming red flags.
Compare the confidence intervals. The 99% confidence interval estimate of the proportion is 0.398< p<0.512 and 0.427< p<0.483, and identify the interval that is wider. Why is it wider?
The 80% confidence interval is wider than the 99% confidence interval. A confidence interval must be wider in order to be more confident that it captures he true value of the population proportion.
The 80% confidence interval is wider than the 99% confidence interval. A confidence interval must be wider in order to be less confident that it captures he true value of the population proportion.
The 99% confidence interval is wider than the 80% confidence interval. A confidence interval must be wider in order to be more confident that it captures he true value of the population proportion.
The 99% confidence interval is wider than the 80% confidence interval. A confidence interval must be wider in order to be less confident that it captures he true value of the population proportion.
3. The 99% confidence interval is wider than the 80% confidence interval. A confidence interval must be wider in order to be more confident that it captures he true value of the population proportion
An IQ test is designed so that the mean is 100 and the standard deviation is 12 for the population of normal adults. It can be said with 99% confidence that the sample mean is within 3 IQ points of the true mean. Assume that σ = 12 and sample size is 107.
Would it be reasonable to sample this number of students?
Yes, this number of IQ test scores is a fairly small number
No, this number of IQ test scores is a fairly large number
Yes, this number of IQ test scores is a fairly large number
No, this number of IQ test scores is a fairly small number
1. Yes, this number of IQ test scores is a fairly small number
When women were finally allowed to become pilots of fighter jets, engineers needed to redesign the ejection seats because they had been originally designed for men only. The ejection seats were designed for men weighing between 130lb and 191lb. Weights of women are now normally distributed with a mean of 168lb and a standard deviation of 38 lb. Complete parts (a) through (b) below:
A) If 1 woman is randomly selected, find the probability that her weight is between 130 lb and 191 lb.
B) If 31 different women are randomly selected, find the probability that their mean weight is between 130 lb and 191 lb.
a)0.5689
b)0.9996
Find the critical value Zα/2 that corresponds to the given confidence level 93%.
1.81
Archeologists have studied sizes of Egyptian skulls in an attempt to determine whether breeding occurred between different cultures. Listed below are the widths (mm) of skulls from 150 A.D. Construct a 95% confidence interval estimate of the mean skull width.
128.3
137.9
126.3
131.7
143.4
134.9
138.9
129.3
128.87< μ<138.81
Express the confidence interval 0.111 < p < 0.777 in the form p̂± E.
0.444 ± 0.333
A random sample of 861 births in a state included 423 boys. It is believed that among all births, the proportion of boys is 0.506.
A. Construct a 95% confidence interval estimate of the proportion of boys in all births.
B. Do these sample results provide strong evidence against that belief?
There is not strong evidence against 0.506 as the value of the proportion of boys in all births because 0.506 is not contained within the 95% confidence interval.
There is strong evidence against 0.506 as the value of the proportion of boys in all births because 0.506 is contained within the 95% confidence interval.
There is strong evidence against 0.506 as the value of the proportion of boys in all births because 0.506 is not contained within the 95% confidence interval.
There is not strong evidence against 0.506 as the value of the proportion of boys in all births because 0.506 is contained within the 95% confidence interval.
a)0.458< p<0.525
b) 4. There is not strong evidence against 0.506 as the value of the proportion of boys in all births because 0.506 is contained within the 95% confidence interval.
Assume that the amounts of weight that male college students gain during their freshman year are normally distributed with a mean of μ = 1.3 kg and a standard deviation of σ = 4.7 kg. Complete parts (a) through (b) below.
A. If 1 male college student is randomly selected, find the probability that he gains between 0 kg and 3 kg during freshman year.
B. If 25 male college students are randomly selected, find the probability that their mean weight gain during freshman year is between 0 kg and 3 kg.
a)0.5689
b)0.9996