Showing 1–16 of 42 results

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Over the past 240 months, an investor’s portfolio had a mean monthly return of 0.79%, with a standard deviation
$2.00$1.00Question: Over the past 240 months, an investor’s portfolio had a mean monthly return of 0.79%, with a standard deviation of monthly returns of 1.16%. According to Chebyshev’s inequality, what is the minimum number of the 240 monthly returns that fall into the range 0.95% to 2.53%?

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Question: Here is the probability of the number of people that will call out of work on average on a daily basis from my office
$2.00$1.00Question: Here is the probability of the number of people that will call out of work on average on a daily basis from my office
x: # of People Calling Out P(x) : Probability 2 0.2 3 0.3 4 0.2 5 0.1 6 0.2 If you are a new manager, and you want to plan for how many people may call out of work tomorrow, what would you expect?

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A different sample of size n = 20 produced a sample mean of 31.08% and a sample standard deviation of 5.48%.
$2.00$1.00Question:
A different sample of size n = 20 produced a sample mean of 31.08% and a sample standard deviation of 5.48%. Use these values to calculate a 90% confidence interval for the national mean percent of lowincome working families. Please show all calculations and provide the upper and lower limits that make up the confidence interval. (Round the limits to two decimal places).

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Curing diabetes: Vertical banded gastroplasty is a surgical procedure that reduces the volume of the stomach
$2.00$1.00Question
Curing diabetes: Vertical banded gastroplasty is a surgical procedure that reduces the volume of the stomach in order to produce weight loss. In a recent study, 82 patients with Type 2 diabetes underwent this procedure, and 59 of them experienced a recovery from diabetes. Does this study provide convincing evidence that greater than 58% of those with diabetes who undergo this surgery will recover from diabetes? Use the a = 0.10 level of significance and the Pvalue method with the TI84 calculator. Source: New England Journal of Medicine 357:753761
State the null and alternate hypotheses.
Но: р (select)______
H1 p (select) ______
This hypothesis test is a (select) test

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A random sample of the number of farms (in thousands) in various states follows. Estimate the mean number of farms per state with 90 % confidence
$2.00$1.00Question:
A random sample of the number of farms (in thousands) in various states follows. Estimate the mean number of farms per state with 90 % confidence.
a) Assume population standard deviation is known and is equal to 31.
b) Assume that population standard deviation is not known.
47 95 54 33 64 48 57 9 80 8 90 3 49 4 44 79 80 48 16 68 7 15 21 52 6 78 109 40 50 29 5.

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A manufacturer would like to determine if the variance in a product dimension exceeds 10
$3.00$2.00Question:
A manufacturer would like to determine if the variance in a product dimension exceeds 10.
a) State the Hypothesis to show the variance is greater than 10.
b) Choose a level of a Use a= 0.05 for this problem.
c) To test the hypothesis, the manufacturer takes a sample of 18 parts and measure that product dimension. The data appear in the Dimension worksheet of the HW3 data workbook on Moodle. Collect data and calculate necessary statistics to test the hypothesis.
d) Sketch the sampling distribution. Include the critical value and test statistic.
e) Draw a conclusion and report that in the problem context.
f) What is the pvalue for the hypothesis test?
Part 1 2 3 4 5 6 7 8 9 Data 48.3 48.5 54 49.3 48.8 56.6 45.8 55.2 45 Part 10 11 12 13 14 15 16 17 18 Data 52 46.4 51.2 50.4 47.6 45.1 44.8 44.9 56.3 
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The waiting time (in minutes) for customers at a driveinbank is an exponentially distributed
$2.00$1.00Question:
The waiting time (in minutes) for customers at a driveinbank is an exponentially distributed random variable. The average(mean) time a customer waits is 4 minutes. What is the probability that a customer waits more than 5 minutes?

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The life in hours of an electronic sensor is known to be approximately Normally distributed
$3.00$2.00Question:
The life in hours of an electronic sensor is known to be approximately Normally distributed, with population standard deviation = hours. A random sample of 10 sensors resulted in the following data: 500,550,560,575,525,505,510,540,550,545.
 Is there evidence to support the claim that mean life exceeds 520 hours? Use a fixedlevel test with alpha = 0.05.
 What is the Pvalue of this test? Conclude the same of part (a)?
 What is the Betavalue for this test if the true mean life is 535 hours?
 What sample size would be required to ensure that Beta does not exceed 0.10 if the true mean life is 540 hours?
 Construct a 95% onesided lower CI on the mean life.
 Use the CI found in part e) to test the hypothesis.

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Suppose that 32% of all users the Infinity Affinity Web site drink diet soft drinks regularly
$2.00$1.00Question:
Suppose that 32% of all users the Infinity Affinity Web site drink diet soft drinks regularly. What is the probability that in survey of a randomly selected sample of 200 of the site’s users, the proportion who say that they drink diet soft drinks regularly will be 40% or less? (Show your work. As part of your answer, you should confirm that the sampling distribution of p is approximately Normal.)

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Last month the waiting time at the drive through window of a fastfood restaurant was 3.7 minutes
$2.00$1.00Question:
Last month the waiting time at the drivethrough window of a fastfood restaurant was 3.7 minutes. The franchise has installed a new process intended to reduce waiting time. After the installation, a random sample of 64 orders is selected. The sample mean waiting time is 3.57 minutes with a sample standard deviation of 0.8 minutes. At a 5% level of significance, is there sufficient evidence that the population mean waiting time is now less than 3.7 minutes? What is your conclusion?

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Based on a random sample of 1040 adults, the mean amount of sleep per night is 7.73 hours
$2.00$1.00Question:
Based on a random sample of 1040 adults, the mean amount of sleep per night is 7.73 hours. Assuming the population standard deviation for amount of sleep per night is 3.5 hours. Construct and interpret a 90% confidence interval for the mean amount of sleep per night.
A 90% confidence interval is ( _____ , ______ ) 
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A parcel service to establish a weight value c, beyond which there will be an additional charge. The weight of parcels handled by this service is Normally distributed
$2.00$1.00Question: Normal Distribuion Probability
A parcel service to establish a weight value c, beyond which there will be an additional charge. The weight of parcels handled by this service is Normally distributed with a mean of 7 kg and a standard deviation of 2.1 kg.
 What value for c (in kg) will insure that only 2.5% of handled package are assessed the additional charge? (Give decimal answer to two places past decimal.)
 What value for c (in kg) will insure that only 1.0% of the handled packages are assessed the additional charge? (Give decimal answer to two places past decimal.)

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A manufacturer of pharmaceutical products analyses each batch of a product to verify the concentration of the active ingredient. The chemical
$2.00$1.00Question: confidence interval for mean
A manufacturer of pharmaceutical products analyses each batch of a product to verify the concentration of the active ingredient. The chemical analysis is not perfectly precise. In fact, repeated measurements follow a Normal distribution with mean μ equal to the true concentration and standard deviation σ = 0.0076 grams per litter. Three analyses of one batch give concentrations 0.8412, 0.8307, and 0.8321 g/l. To estimate the true concentration, give a 95% confidence interval for μ. (Round your answers to four decimal places.)

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A random sample of size 12 from a normal population is given below. 69 74 75 76 78 79 81 83 83 85 86 87
$2.00$1.00Question: A random sample of size 12 from a normal population is given below.
69 74 75 76 78 79 81 83 83 85 86 87
a) Someone claimed that s = 10. Does this data set support the claim? Test at a = 0.05.
b) Test if the population mean is 85 using a = 0.05.
c) Find the pvalue of the test 
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Congress regulates corporate fuel economy and sets an annual gas mileage for cars.
$3.00$2.00Question: Congress regulates corporate fuel economy and sets an annual gas mileage for cars. A company with a large fleet of cars hopes to meet the goal of 30.4 mpg or better for their fleet of cars. To see if the goal is beingmet, they check the gasoline usage for 46 company trips chosen at random, finding a mean of 31.4 mpg and a standard deviation of 2.57 mpg. Is this strong evidence that they have attained their fuel economy goal? Use 0.05 as the level of significance. pValue = 0.006. State an appropriate conclusion. Choose the correct answer below.

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Using the following data on candidates for the Virginia state legislature: 1) Calculate the slope and intercept for the regression line. Write out the equation model. Be sure to show your work.
$4.00$3.00Question: Using the following data on candidates for the Virginia state legislature:
 Calculate the slope and intercept for the regression line. Write out the equation model. Be sure to show your work.
 Interpret the slope and intercept.
Candidate for Virginia General Assembly X = number of years in state politics Y = votes received in Albemarle County Isabelle 18 2300 Benjamin 5 2950 Sophia 12 1780 Jacob 2 3120