A survey asked senior executives at large corporations their opinions about the economic outlook for the future. One question was, "Do you think that there will be an increase in the number of full-time employees at your company over the next 12 months?" In the current survey, 220 of 400 executives answered Yes, while in a previous year survey, 168 of 400 executives had answered Yes. Provide a 95% confidence interval estimate for the difference between the proportions at the two points in time. (Use current year − previous year. Round your answer to four decimal places.) _______ to _________

A survey is taken of 250 students, and a P of 0.45 is found. The same survey is repeated with 1,000 students, and the same value is found. Compare the two 95% confidence intervals. What is the relationship? Is the margin of error for the second one four times smaller? How much smaller is it?

If you want to be confident in your estimation of a confidence interval, you should use….

If two people used the same data and one person made a 90% confidence interval and the other person made a 95% confidence interval for p, which interval would be more narrow?   is it; a. The 90% Confidence interval b. The 95% Confidence interval c. We cannot tell from the information alone.

A survey of 32,782 adults in 2004 indicated that 24.6% of adults were current smokers. A similar study conducted in 1995 of 40,000 adults indicated that 29.7% were current smokers. a. Find and interpret a point estimate of the difference between the proportion of current smokers in 1995, and the proportion of current smokers in 2004. b. A 95% confidence interval for the true difference is (-0.058,-0.045). Interpret. c. What assumptions must you make for the confidence interval i part b to be valid? (…) a. Find a point estimate of the difference between the proportion of current smokers in 1995 and the proportion of current smokers in 2004. (Round to three decimal places as needed.)

1. The data in Table 7–6 were collected in a clinical trial to evaluate a new compound designed to improve wound healing in trauma patients. The new compound was com- pared against a placebo. After treatment for 5 days with the new compound or placebo, the extent of wound healing was measured. Is there a difference in the extent of wound healing between the treatments? (Hint: Are treatment and the percent wound healing independent?) Run the appropriate test at a 5% level of significance. Use the data in Problem 1. Pool the data across the treatments into one sample of size n = 250. Use the pooled data to test whether the distribution of the percent wound healing is approximately normal. Specifically, use the following distribution 30%, 40%, 20%, and 10% and a = 0.05 to run the appropriate test.   Percent Wound Healing   Treatment 0-25% 26-50% 51-75% 76-100% New compound (n=125) 15 37 32 41 Placebo (n=125) 36 45 34 10

Suppose NBC has asked the same question to a sample of 1296 adults nine months earlier, finding 47% with an optimistic outlook for the year ahead.  Develop a 95% confidence interval for the percentage of American adults who had an optimistic outlook for the economy nine months earlier.

The picture is attached. If it is not clear, the shaded region of the graph represents 5%. Thanks in advance.

It seems that  of engaged women buy a wedding dress at least one size smaller than their current size. Why? Cornell researchers reported an alarming tendency for women who are engaged to sometimes attempt to lose an unhealthy amount of weight prior to their wedding (Neighbors & Sobal, 2008). The researchers found that engaged women weighed, on average, 152.1 pounds. The average ideal wedding weight reported by 227 women was 136.0 pounds. The data below represent the fictional weights of eight women on the day they bought their wedding dress and on the day they got married. Did women lose weight for their wedding day? Dress purchase Wedding day 163 158 144 139 151 150 120 118 136 132 158 152 155 150 145 146 Conduct the six steps of hypothesis testing using a one-tailed test and an alpha level of 0.05. Report the test statistic in APA format. Calculate the confidence interval for the paired-samples t test that you conducted in part (a). Compare the…

Estimating income tax based on dividends is also not​ straightforward, due in part to​ Australia’s franking credit scheme.​ Mike is looking to simplify total annual tax projections for a share portfolio based simply on the share​ portfolio's current value. To do​ this, he wishes to determine if there is any statistically significant linear relationship between the two.   Mike has randomly sampled 30 individuals with share portfolios over​ AUD$100,000 and mapped the assessed value of the portfolio​ (in AUD​ $1000) to the total taxes paid on that amount​ (in AUD$1). ​ Mike's data is in the table below.   Assessed Value Taxes 426.1 5014 368.8 3698 309.8 3691 373.9 5189 445.7 4455 505.1 5189 342.3 3416 343.6 3931 432.3 4393 329.2 3267 291.2 2871 399.3 4013 392.7 4728 482.2 4885 480.6 4888 390.8 3917 371.6 3738 311.9 3098 343.7 3633 304.7 3538 274.6 3427 457.1 4633 231.5 4009 450.5 4565 510.1 5946 308.4 3045 348.8 3504 410.4 3375…