1. Concerns about climate change and CO₂reduction have initiated the commercial production of blends of biodiesel (e.g., from renewable sources) and petrodiesel (from fossil fuel). Random samples of 41 blended fuels are tested in a lab to ascertain the bio/total carbon ratio.

(a)If the true mean is .9220 with a standard deviation of 0.0060, within what interval will 90 percent of the sample means fall?(Round your answers to 4 decimal places.)

The interval is from _______to______

2. Find the standard error of the mean for each sampling situation (assuming a normal population).(Round your answers to 2 decimal places.)

Standard Error

(a) = 44, n = 16 ____________

(b) = 44, n = 64 ____________

(c) = 44, n = 256 ___________

3. The highway fuel economy of a 2016 Lexus RX 350 FWD 6-cylinder 3.5-L automatic 5-speed using premium fuel is a normally distributed random variable with a mean of = 20.25mpg and a standard deviation of = 2.25mpg.

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(a)What is the standard error ofX, the mean from a random sample of 16 fill-ups by one driver?(Round your answer to 4 decimal places.)

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Standard error ofX _____________

(b)Within what interval would you expect the sample mean to fall, with 90 percent probability?(Round your answers to 4 decimal places.)

The interval is from______to__________

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4. Use the sample informationx= 40,= 3,n= 18 to calculate the following confidence intervals forassuming the sample is from a normal population.

(a)90 percent confidence.(Round your answers to 4 decimal places.)

The 90% confidence interval is from_____to______

(b)95 percent confidence.(Round your answers to 4 decimal places.)

The 95% confidence interval is from_______to_________

(c)99 percent confidence.(Round your answers to 4 decimal places.)

The 99% confidence interval is from_________to________

5. The Ball Corporation's beverage can manufacturing plant in Fort Atkinson, Wisconsin, uses a metal supplier that provides metal with a known thickness standard

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deviation= .000507 mm. Assume a random sample of 53 sheets of metal resulted in anx = .3333 mm.

Calculate the 90 percent confidence interval for the true mean metal thickness.(Round your answers to 4 decimal places.)

The 90% confidence interval is from_________to________

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6. A random sample of 28 items is drawn from a population whose standard deviation is unknown. The sample mean isx= 790 and the sample standard deviation iss= 15. UseAppendix Dto find the values of Student'st.

(a)Construct an interval estimate ofwith 99% confidence.(Round your answers to 3 decimal places.)

The 99% confidence interval is from_____to______

(b)Construct an interval estimate ofwith 99% confidence, assuming thats= 30.(Round your answers to 3 decimal places.)

The 99% confidence interval is from______to_______

(c)Construct an interval estimate ofwith 99% confidence, assuming thats= 60.(Round your answers to 3 decimal places.)

The 99% confidence interval is from______to______

7. A random sample of 16 pharmacy customers showed the waiting times below (in minutes).

22 14 25 15 19 15 17 21

15 16 23 16 29 21 22 21

Find a 90 percent confidence interval for, assuming that the sample is from a normal population.(Round your standard deviation answer to 4 decimal places and t-value to 3 decimal places. Round your answers to 3 decimal places.)

The 90% confidence interval_______to________

8. Calculate the standard error. May normality be assumed?(Round your answers to 4 decimal places.)

Standard Error

(a)n= 30,= .50 ___________

(b)n= 50,= .20 ___________

(c)n= 100, = .10 ____________

(d)n= 500, = .005 ____________

9. Of 43 bank customers depositing a check, 23 received some cash back.

(a)Construct a 90 percent confidence interval for the proportion of all depositors who ask for cash back.(Round your answers to 4 decimal places.)

The 90% confidence interval is from_______to_________