Which Of The Following Is A Good Point Estimator For The Population Variance?

**S^2**

Often leads to biased studies (not recommended).

If the claim is true, what is the probability that the mean monitor life would be greater than 91.4 months in a sample of 66 monitors? Round your answer to four decimal places.

first, find the standard error

σ=Standard Deviation of the population=9

n=Sample Size=66

σx‾=√σ2/n= σ/√n = 9/√66 ≈ 1.107823

P(x‾>91.4)=P(x‾−μ/σx‾>91.4−93/1.107823) =P(z>91.4−93/1.107823)

≈P(z>−1.44)

Correct Answer:0.9251

If the claim is true, in a sample of 41 wall clocks, what is the probability that the mean clock life would be greater than 15.4 years? Round your answer to four decimal places.

15.4-15=.4/0.7809

Correct Answer:0.3043

What is the probability that the sample mean would be less than 18850 dollars if a sample of 333 persons is randomly selected? Round your answer to four decimal places.

18850-18,904=-54/25.7010

≈P(z<−2.10)

Correct Answer: 0.0178

If 41 racing cars are randomly selected, what is the probability that the sample mean would be greater than 84.1 gallons? Round your answer to four decimal places.

84.1-86/1.0932

≈P(z>−1.7380)

Correct Answer: 0.9589

If 142 adults are randomly selected, what is the probability that the sample mean would differ from the population mean by more than 1.5 kilograms? Round your answer to four decimal places.

10/√142≈0.8391813583

Since the true value of the population mean is 76, the value of x‾ should not fall between 74.5 and 77.5 in order for the error of estimation to be more than 1.5.

Correct Answer: 0.0739

What is the probability that the sample mean would differ from the true mean by more than 1.2 dollars if a sample of 188 5-gallon pails is randomly selected? Round your answer to four decimal places.

Since the true value of the population mean is 39, the value of x‾ should not fall between 37.8 and 40.2 in order for the error of estimation to be more than 1.2 dollars.

Correct Answer: 0.0187

If a random sample of 41 steel bolts is selected, what is the probability that the sample mean would differ from the population mean by more than 2.1mm? Round your answer to four decimal places.

8/√141=1.249390095

Since the true value of the population mean is 139, the value of x‾ should not fall between 136.9 and 141.1 in order for the error of estimation to be more than 2.1mm.

Correct Answer: 0.0928

If a sample of 74 televisions is randomly selected, what is the probability that the sample mean would differ from the true mean by less than 1.1 months? Round your answer to four decimal places.

Since the true value of the population mean is 119, the value of x‾ should not fall between 117.9 and 120.1 in order for the error of estimation to be more than 1.1.

Correct Answer: 1.627466942

If he is correct, what is the probability that the mean of a sample of 90 computers would be less than 117.13 months? Round your answer to four decimal places.

Correct Answer: 0.0032

If a random sample of 43 steel bolts is selected, what is the probability that the sample mean would be greater than 132.4 millimeters? Round your answer to four decimal places.

Correct Answer: 0.7440

What is the probability that the mean weight of the sample of horses would differ from the population mean by less than 9lbs if 49 horses are sampled at random from the stable? Round your answer to four decimal places.

Since the true value of the population mean is 1467, the value of x‾ must fall between 1458 and 1476 in order for the error of estimation to be less than 9.

Correct Answer: 0.5019

If 56 amplifiers are sampled, what is the probability that the mean of the sample would differ from the population mean by less than 1.8 watts? Round your answer to four decimal places.

Since the true value of the population mean is 287, the value of x‾ must fall between 285.2 and 288.8 in order for the error of estimation to be less than 1.8.

Correct Answer: 0.8220

What is the probability that the sample mean would differ from the population mean by less than 219 miles in a sample of 178 tires if the manager is correct? Round your answer to four decimal places.

4103.000122/√178=307.5328611

Since the true value of the population mean is 28,631 miles, the value of x‾ must fall between 28412 and 28850 in order for the error of estimation to be less than 219.

Correct Answer: 0.5236