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A doctor wants to estimate the HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the HDL cholesterol within 4 points with 99% confidence assuming σ=11.7? Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample size required?

use the confidence interval to find the estimated margin of error. Then find the sample mean.

A biologist reports a confidence interval of left parenthesis (2.1,2.9) when estimating the mean height (in centimeters) of a sample of seedlings.

Find the critical value z Subscript czc necessary to form a confidence interval at the level of confidence shown below.

Match the level of confidence, cequals=0.950.95, with its representation on the number line, given x overbar equals 56.7x=56.7, sequals=8.88.8, and nequals=9090.

Choose the correct number line below.

A.

53

54

55

56

57

58

59

60

61

54.2

59.2

x overbar equals 56.7x=56.7

B.

53

54

55

56

57

58

59

60

61

54.9

58.5

x overbar equals 56.7x=56.7

C.

53

54

55

56

57

58

59

60

61

54.5

58.9

x overbar equals 56.7x=56.7

D.

53

54

55

56

57

58

59

60

61

55.2

58.2

x overbar equals 56.7x=56.7

The confidence interval is (54.88, 58.52), so it appears that choice B is what they are looking for.

Homework: Homework 3 (Read 5.1 to 5.4 and 6.1 to 6.3) Save

Score: 0 of 1 pt 49 of 81 (71 complete)

HW Score: 84.25%, 84.25 of 100 pts

Construct the confidence interval for the population mean muμ.

cequals=0.980.98, x overbar equals 4.9x=4.9, sequals=0.30.3, and nequals=4848

A 9898% confidence interval for muμ is left parenthesis nothing comma nothing right parenthesis .

Find the minimum sample size n needed to estimate muμ for the given values of c, s, and E.

cequals=0.980.98, sequals=8.18.1, and Eequals=22

Assume that a preliminary sample has at least 30 members.

nequals=

You are given the sample mean and the sample standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. If convenient, use technology to construct the confidence intervals.

A random sample of 6060 home theater systems has a mean price of $119.00119.00 and a standard deviation is $15.3015.30.

Construct a 90% confidence interval for the population mean.

The 90% confidence interval is left parenthesis nothing comma nothing right parenthesis

.In a survey of 10201020 adults, 803803 disapprove of the job the legislature is doing.

Use technology to construct 90%, 95%, and 99% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals.

A 90% confidence interval for the population proportion is left parenthesis nothing comma nothing right parenthesis

In a survey of 10271027 adults, 805805 disapprove of the job the legislature is doing.

Use technology to construct 90%, 95%, and 99% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals.

A 90% confidence interval for the population proportion is left parenthesis nothing comma nothing right parenthesis.In a survey of 10271027 adults, 805805 disapprove of the job the legislature is doing.

Use technology to construct 90%, 95%, and 99% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals.

A 90% confidence interval for the population proportion is left parenthesis nothing comma nothing right parenthesis

In a survey of 10271027 adults, 805805 disapprove of the job the legislature is doing.

Use technology to construct 90%, 95%, and 99% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals.

A 90% confidence interval for the population proportion is left parenthesis nothing comma nothing right parenthesis

A beverage company uses a machine to fill one-liter bottles with water (see figure). Assume that the population of volumes is normally distributed.

(a) The company wants to estimate the mean volume of water the machine is putting in the bottles within 1 milliliter. Determine the minimum sample size required to construct a 9090% confidence interval for the population mean. Assume the population standard deviation is 55 milliliters.

(b) Repeat part (a) using an error tolerance of 22 milliliters. Which error tolerance requires a larger sample size? Explain.

If a random variable x is normally distributed, you can find the probability that x will fall in a given interval by calculating the area under the normal curve for the given interval. To find the area under the normal curve, first convert the upper bound of the interval to a z-score. Use either technology or the standard normal table to find the area corresponding to the z-score. To convert the area to a percent multiply by 100.

Use the normal distribution of SAT critical reading scores for which the mean is 510510 and the standard deviation is 114114. Assume the variable x is normally distributed.

left parenthesis a right parenthesis(a)

What percent of the SAT verbal scores are less than 550550?

left parenthesis b right parenthesis(b)

If 1000 SAT verbal scores are randomly selected, about how many would you expect to be greater than 525525?

left parenthesis a right parenthesis(a) Approximately

nothing% of the SAT verbal scores are less than 550550.

(Round to two decimal places as needed.)

A doctor wants to estimate the HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the HDL cholesterol within 44 points with 99 %99% confidence assuming sigma equals 13.7 question mark σ=13.7? Suppose the doctor would be content with 90 %90% confidence. How does the decrease in confidence affect the sample size required?