In a survey of

24562456

adults in a recent​ year,

13921392

say they have made a New​ Year's resolution.

Construct​ 90% and​ 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals.

Please show work and explain.

To test the effectiveness of a business school preparation course, 9 students took a general business test before and after the course. The results:

(a) Use an appropriate hypothesis test, at 0.01 level of significance, to determine whether there is evidence of a difference between before and after scores of the students.

(b) What assumption is necessary to perform the hypothesis test in (a)?

(c) Construct a 99% confidence interval estimate of the mean difference in before and after scores. Interpret the interval. What is your decision based on this confidence interval estimate?

(d) Compare the results in (a) and (c).

Can you answer the following showing working and formula used.

The length of a screw manufactured by a company is normally distributed with mean 2.5cm and a standard deviation 0.1cm. Specifications call for the lengths to range from 2.4cm to 2.6 cm.

a, What proportion of parts will be greater than 2.65cm?

b, What length is exceeded by 10% of the parts?

c, What percentage of parts will not meet the specification?

d, If you randomly pick three of those items, what would be the probability that exactly two of them will meet the specification?

e, What value of the standard deviation is required so that less than 7% of screws have a length greater then 2.8CM?

f, Another manufacturer produces the same screw for which 15% of the screws have length less than 1.75cm and 12% of the screws have length higher than 3.20cm. Find the mean and standard deviation of the length of screw manufactured by the company assuming the length is normally distributed.`

The U.S. Dairy Industry wants to estimate the mean yearly milk consumption. A sample of 20 people reveals the mean yearly consumption to be 72 gallons with a standard deviation of 15 gallons. Assume the population distribution is normal. (Use t Distribution Table.)

What is the best estimate of this value?

For a 99% confidence interval, what is the value of t? (Round your answer to 3 decimal places.)

Develop the 99% confidence interval for the population mean. (Round your answers to 3 decimal places.)

A certain region would like to estimate the proportion of voters who intend to participate in upcoming elections. A pilot sample of 25 voters found that 17 of them intended to vote in the election. Determine the additional number of voters that need to be sampled to construct a 99​% interval with a margin of error equal to 0.07 to estimate the proportion.

The region should sample ___________ additional voters. ​(Round up to the nearest​ integer.)

_______________________________________________________________________________________________________________________________________________

Determine the sample size n needed to construct a 90​% confidence interval to estimate the population proportion for the following sample proportions when the margin of error equals 4​%.

a. p overbar=0.20

b. p overbar=0.30

c. p overbar=0.40

a. n=___________(Round up to the nearest​ integer.)

2. (a) Yuk Ping belongs to an athletics club. In javelin throwing competitions her throws
are normally distributed with mean 41.0 m and standard deviation 2.0 m.
(i) What is the probability of her throwing between 40 m and 46 m?
(ii) What distance will be exceeded by 60% of her throws?

(b) Gwen belongs to the same club. In competitions 85% of her javelin throws exceed
35 m and 70% exceed 37.5 m. Her throws are normally distributed.
(i) Find the mean and s.d. of Gwen's throws, each correct to two decimal places.
(ii) What is the probability that, in a competition in which each athlete takes a
single throw, Yuk Ping will beat Gwen?
(iii) The club has to choose one of these two athletes to enter a major competition.
In order to qualify for the final rounds it is necessary to achieve a throw of at
least 48 m in the preliminary rounds. Which athlete should be chosen? Why?

When doing regression, simple linear or any of the other regression approaches, the analyst always must begin with the determination/isolation of at least two key variables -- one "dependent" and the other "independent". So, for example, I may do a forecast of future profits that relies on sales data (independent) and associated profit data (dependent) from the same years. We say something like...

"Since profits "depend" on sales volume (not the other way around), we can use one (sales) to forecast the other (profit)."

Find an example of a regression model with Google. Then explain which variables used in the model are "dependent" vs. "independent."

For this problem, carry at least four digits after the decimal in your calculations. Answers may vary slightly due to rounding. Santa Fe black-on-white is a type of pottery commonly found at archaeological excavations at a certain monument. At one excavation site a sample of 610 potsherds was found, of which 350 were identified as Santa Fe black-on-white.

(a) Let p represent the proportion of Santa Fe black-on-white potsherds at the excavation site. Find a point estimate for p. (Round your answer to four decimal places.)

(b) Find a 95% confidence interval for p. (Round your answers to three decimal places.) lower limit upper limit Give a brief statement of the meaning of the confidence interval. 95% of the confidence intervals created using this method would include the true proportion of potsherds. 5% of all confidence intervals would include the true proportion of potsherds. 95% of all confidence intervals would include the true proportion of potsherds. 5% of the confidence intervals created using this method would include the true proportion of potsherds.

(c) Do you think that np > 5 and nq > 5 are satisfied for this problem? Explain why this would be an important consideration. Yes, the conditions are satisfied. This is important because it allows us to say that p̂ is approximately normal. Yes, the conditions are satisfied. This is important because it allows us to say that p̂ is approximately binomial. No, the conditions are not satisfied. This is important because it allows us to say that p̂ is approximately binomial. No, the conditions are not satisfied. This is important because it allows us to say that p̂ is approximately normal.

Bob Nale is the owner of Nale’s Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal distribution with a population standard deviation of 2.00 gallons. From his records, he selects a random sample of 65 sales and finds the mean number of gallons sold is 9.10.

What is the point estimate of the population mean?

Develop a 98% confidence interval for the population mean. (Use z Distribution Table.)

SPC Project

A small electronic device is designed to emit a timing signal of 200 milliseconds (ms) duration. In the production of this device, 20 samples of five units are taken and tested. and R are calculated for each sample and used to plot control charts. The results are shown in the following table.

a. Compute the averages, upper control limits, and lower control limits for and R charts for this data. Use the equations on pages 194-195 of your text, and Table 6.1 (page 195) for A2, D3, and D4.

b. Plot the R and charts in Excel. Is the process in statistical control?

c. Estimate the standard deviation of the process (σ) from the range data. σ = /d2, where d2 = 2.326 for a sample size of 5.

d. Assuming that the distribution of the data is approximately normal, what proportion of the devices would you expect to meet specifications of Lower Specification Limit = 190.5 and Upper Specification Limit = 210.5? Use the estimate of the standard deviation you calculated in part c.

Let Y denote a random variable that has a Poisson distribution with mean λ = 3. (Round your answers to three decimal places.)

(a) Find P(Y = 6)

(b) Find P(Y ≥ 6)

(c) Find P(Y < 6)

(d) Find P(Y ≥ 6|Y ≥ 3).

In the video, studies of twins were used to add evidence to a debate about whether an individual's character is formed primarily from their genetics or their environment. Review your course readings and answer the following questions related to the Nature or Nurture debate

In your own words, explain how the use of twin studies can help to clarify whether characteristics are determined primarily by genes or environment.

The assumption made in this debate is that factors in an individual’s genetic make-up, or in their environment, cause how they act as adults. Discuss whether you agree with that assumption and why or why not.

In your opinion, does the high degree of correlation between the behavior of twins prove that genetics causes their behavior?

Why might you question how well one variable predicts another, such as whether genes or environment predicts adult behavior?

Thinking about your own life experiences, describe reasons why your genetics or childhood environment might fail to predict your current decisions and actions.

Is college worth it? Among a simple random sample of 344 American adults who do not have a four-year college degree and are not currently enrolled in school, 166 said they decided not to go to college because they could not afford school.

1. Calculate a 90% confidence interval for the proportion of Americans who decide to not go to college because they cannot afford it, and interpret the interval in context. Round to 4 decimal places.

2. Suppose we wanted the margin of error for the 90% confidence level to be about 2.25%. What is the smallest sample size we could take to achieve this? Note: For consistency's sake, round your z* value to 3 decimal places before calculating the necessary sample size.

choose n=

Choice blindness is the term that psychologists use to describe a situation in which a person expresses a preference and then doesn't notice when they receive something different than what they asked for. The authors of the paper "Can Chocolate Cure Blindness? Investigating the Effect of Preference Strength and Incentives on the Incidence of Choice Blindness"† wondered if choice blindness would occur more often if people made their initial selection by looking at pictures of different kinds of chocolate compared with if they made their initial selection by looking at the actual different chocolate candies.

Suppose that 200 people were randomly assigned to one of two groups. The 100 people in the first group are shown a picture of eight different kinds of chocolate candy and asked which one they would like to have. After they selected, the picture is removed and they are given a chocolate candy, but not the one they actually selected. The 100 people in the second group are shown a tray with the eight different kinds of candy and asked which one they would like to receive. Then the tray is removed and they are given a chocolate candy, but not the one they selected.

If 22 of the people in the picture group and 13 of the people in the actual candy group failed to detect the switch, would you conclude that there is convincing evidence that the proportion who experience choice blindness is different for the two treatments (choice based on a picture and choice based on seeing the actual candy)? Test the relevant hypotheses using a 0.01 significance level. (Let p₁ be the proportion who experience choice blindness based on a picture treatment, and p₂ be the proportion who experience choice blindness based on seeing the actual candy treatment.)

Find the test statistic and p-value.