A sample of 52 Elementary Statistics students includes 13 women. Assuming the sample is 4. random. . .

(a) Estimate the percentage of women taking Elementary Statistics with 98% confidence.

(b) At 10% significance, test whether less than 40% of the enrollment in all Elementary Statistics classes consists of women.

(c) If in fact 46% of the students in Elementary Statistics classes are women, find the power of the above test in detecting this parameter.

The GPAs of all 5540 students enrolled at a university has a distribution with a mean of 3.02 and a standard deviaiton of 0.29. Let x-bar be the mean GPA of a random sample of 48 students selected from this university.

a. Find the mean and standard deviation of x-bar and comment on the shape of its sampling distribution (1 point for each).

b. What is the probability that the sample mean of such a sample will be greater than 3.10?

Consider the following frequency table representing the distribution of hours students study for an exam in a week. Hours Students Study for an Exam in a Week

Class Frequency

17–27 13

28–38 15

39–49 11

50–60 15

61–71 2

Step 1 of 2:

Determine the cumulative frequency for the fifth class.

Step 2 of 2: Determine the cumulative frequency for the second class.

In a random sample of 600 U.S. high school students, 11% (or 66 out of 600) said they do not plan on having children.

What sample size would allow us to create a 99% confidence interval for the true proportion of U.S. high school students who do not plan on having children with a margin of error of only 0.02?

Group of answer choices

1083

459

220

1625

882

Exhibit F
In order to estimate the average time that students spend on the internet per day, data were collected for a sample of 36 business students. Assume the population standard deviation is 2 hours.

Refer to Exhibit F. If the sample mean is 6 hours, then the 95% confidence interval for the population mean,μ, is

Group of answer choices

4.35 to 7.65

5.67 to 6.33

5.35 to 6.65

6 to 6.65

The student academic group on a college campus claims that freshman students study at least 2.5 hours per day, on average. One Introduction to Statistics class was skeptical. The class took a random sample of 30 freshman students and found a mean study time of 137 minutes with a standard deviation of 45 minutes. At α = 0.01 level, is the student academic group’s claim correct? Calculate the p-value.

One college class had a total of 80 students. The average score for the class on the last exam was 84.3 with a standard deviation of 5.4. A random sample of 34 students was selected.

a. Calculate the standard error of the mean.

b. What is the probability that the sample mean will be less than 86?

c. What is the probability that the sample mean will be more than 85?

d. What is the probability that the sample mean will be between 83.5 and 85.5?

it takes careful analysis to determine the actual cause and effect of a breakdown / problem. Although many of you have taken statistics courses by now, I find that many students are not confident with their analytical skills. These are important skills to develop and your abilities and confidence will improve with experience. Many students are able to do the mathematical analysis, but cannot put the results into practical application. What changes does your analysis suggest?

Three students answer a true-false question on a test randomly. A random variable x represents the number of answers of true among the three students, taking on the value 0, 1, 2, or 3.

(a) Find the frequency distribution for x.
(b) Find the probability distribution for x.

For the same random variable x as the previous problem, find the following:

(a) The expected value (b) The variance (c) The standard deviation