A poll is taken in which 332 out of 500 randomly selected voters indicated their preference for a certain candidate.

(a) Find a 90% confidence interval for pp.

≤p≤

(b) Find the margin of error for this 90% confidence interval for p.

Reconsider the portfolio selection example, including its spreadsheet model in Figure 8.13, given in Section 8.2. Note in Table 8.2 that Stock 2 has the highest expected return and stock 3 has by far the lowest. Nevertheless, the changing cells Portfolio (C14:E14) provide an optimal solution that calls for purchasing far more of Stock 3 than of Stock 2. Although pur- chasing so much of Stock 3 greatly reduces the risk of the portfo- lio, an aggressive investor may be unwilling to own so much of a stock with such a low expected return.
For the sake of such an investor, add a constraint to the model that specifies that the percentage of Stock 3 in the portfolio can- not exceed the amount specified by the investor. Then compare the expected return and risk (standard deviation of the return) of the optimal portfolio with that in Figure 8.13 when the upper bound on the percentage of Stock 3 allowed in the portfolio is set at the following values.
a.   20%

c.   Generate a parameter analysis report using RSPE to
systematically try all the percentages at 5% intervals from 0% to 50%

John invited four friends to his birthday party and his friends will arrive independently of one another. The arrival time x for each friend is uniform over (0; 4) and these arrival times are i.i.d. Answer to the following questions:

(a) the density of the arrival time who arrives at second.
(b) the probability that the second person to arrive between 0 and 2.
(c) the expected arrival time of the second person to arrive.

A survey by American Express Spending reported that the average amount spent on a wedding gift for a close family member is $166. A random sample of 45 people who purchased wedding gifts for a close family member spent an average of $160.50. Assume that the population standard deviation is $38. Use a 95% confidence interval to test the validity of this report and choose the one statement that is correct.

Group Support for Abortion Males Females Totals High 10.64 9.36 20 Low 14.36 12.64 27 Totals 25 22 47 Using the data above, do women and men differ in their opinions about abortion? Complete the chi-square test to make your decision. Show all 5 steps for full credit.

please share a real-life experience where you saw some topic from this class(statistics) being used. Please give the source, identify the topic, and give a little explanation on how it was used.  

we have learned

probability

variances

standard deviations

frequency distrubutions and graphs

Use the data for two Sydney suburbs to answer questions 1-5:

1. Using Excel or other appropriate software, produce two separate histograms for the median rental prices of the two selected suburbs, respectively. Use an appropriate number of bins for your histogram and remember to label the axes. Describe and compare the two histograms, including the central location, dispersion and skewness. [1 mark]

2. Compute the sample means and sample standard deviations of the median rental prices of the two selected suburbs, respectively. No need to show computational steps. [1 mark]

It is claimed that the median rental price for a two-bedroom property in Sydney is $511 per week. To investigate the claim formally, you carry out a hypothesis test – by (1) constructing a confidence interval and:

In particular, the following are two questions you want to examine:

1. whether the average rent in Suburb 1 (or Suburb 2) is equal to $511 per week
2. whether the average rent in one of the suburbs is significantly higher than the other

3. Set up the null and alternative hypotheses. Define the notation(s) clearly. [2 marks]

4. Using StatKey or other appropriate software, produce a dot plot of the bootstrap distribution (with at least 5,000 bootstrap samples) of the appropriate sample statistic for b)

Comment on its shape (e.g., central location, degree of symmetry). [1 mark]

5. With reference to the bootstrap distribution in question 4, construct two 95% bootstrap confidence intervals, one using the percentile method and another one based on normal distributions. What can you conclude at a 5% significance level? [1 mark]

Two Suburbs

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.