A 30 item multiple choice test designed by a researcher was administered to 160 SS2 students and marked. The mean score was 17 and standard deviation was 5.8, if the test was to be a standardized test with 6000 participants and those that got each item right was b
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A 30 item multiple choice test designed by a researcher was administered to 160 SS2 students and marked. The
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- I need help, I keep getting it wrong and only have one more try for each.A researcher wanted to know whether losing one night sleep can affect problem solving. A sample of n = 25 college students was given a problem-solving task at noon on one day and again at noon on the following day. The students were not permitted any sleep between the two tests. For each student, the difference between the first and the second score was recorded: MD = 5 and standard deviation of the difference score was s = 10. Do the data indicate a significant change in problem solving ability? Use a two-tailed test with α = .01. a. The alternative hypothesis in words is b. The null hypothesis in symbols is c. The critical t-values are d. The t-statistic is e. Your decision isA large number of bags of cement have been manufactured. You sample 10 of the bags and find that they have a mean weight of 91.5 pounds with a standard deviation of 8.8 pounds. Find the 90 % confidence limit for the mean of the weight of all of the cement bags.
- An important measure in the study of contagious infectious diseases is the number of cases directly generated by one previous case. Jessica is an epidemiologist studying the spread of an infectious disease in her country. She claimed that the mean number of cases directly generated by one previous case is now greater than 1.2. A study of 12 randomly selected cases of the disease is conducted and finds the sample mean number of cases directly generated by one previous case to be 1.5 with a sample standard deviation of 0.7. Assume that the population of the number of cases directly generated by one previous case is approximately normally distributed. Complete the parts below to perform a hypothesis test to see if there is enough evidence, at the 0.10 level of significance, to support the claim that u, the mean number of cases directly generated by one previous case, is greater than 1.2. (a) State the null hypothesis H, and the alternative hypothesis H, that you would use for the test.…I know the answer to 8 but had to include it to get help with question 10. Thanks.Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 37 randomly selected people who train in groups, and finds that they run a mean of 47.7 miles per week. Assume that the population standard deviation for group runners is known to be 3.3 miles per week. She also interviews a random sample of 49 people who train on their own and finds that they run a mean of 49.4 miles per week. Assume that the population standard deviation for people who run by themselves is 4.4 miles per week. Test the claim at the 0.10 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.
- Researchers are interested in the effect of pet companionship on depression in elderly adults. They randomly select 25 participants from the target population and record their depression scores before and after spending a month with a dog (a higher score indicates a higher level of depression). The researchers then compute the difference scores for each participant (difference after before). The mean of differences is -1 and the standard deviation of differences is 2. Can the researchers conclude that there is an effect of pet companionship on depression in elderly adults? Conduct the appropriate statistical test (two-tailed) with a = .05. Should you reject or fail to reject the null hypothesis? Reject O Fail to rejectA study was conducted to investigate the effect of a new drug on blood pressure. A sample of 25 patients was randomly selected and their blood pressure was measured both before and after taking the drug. The sample mean blood pressure before taking the drug was 120 mmHg and the sample mean blood pressure after taking the drug was 118 mmHg. The sample standard deviation for the blood pressure before taking the drug was 4 mmHg and the sample standard deviation for the blood pressure after taking the drug was 5 mmHg. Test the hypothesis that the average blood pressure after taking the drug is lower than the average blood pressure before taking the drug using a 0.01 level of significance.A maintenance supervisor is comparing the standard version of an instruetional booklet with one that has been claimed to be superior. An experiment is conducted in which 26 technicians are divided into two groups, provided with one of the booklets, then given a test a week later. For the 13 using the standard version, the average exam score was 72.0, with a standard deviation of 9.3. For the other 13 using the new version, the average score was 80.2, with the standard deviation of 10.1. Assume normal populations with equal standard deviations, and using the 5% level of significance, does the standard version booklet appear to be better than the new version?
- Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 42 randomly selected people who train in groups and finds that they run a mean of 47.1 miles per week. Assume that the population standard deviation for group runners is known to be 4.4 miles per week. She also interviews a random sample of 47 people who train on their own and finds that they run a mean of 48.5 miles per week. Assume that the population standard deviation for people who run by themselves is 1.8 miles per week. Test the claim at the 0.01 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.On a measure of running speed on a 100 meter dash, students received timed scores ranging from 12 seconds to 24 seconds. The distribution of running times is normative with a mean of 16 seconds. Transferring this ratio data to standard scores for comparison with the results of classes from other departments, the mean score is assigned a standard score of 100 with a standard deviation of 10. From this example, a standard score of 99 would mean the actual value in seconds for an individual would be about a. 16 b. 12 c. 19 d. 24In Professor Krugman’s economics course, the correlation between the students’ total scores prior to the final examination and their final‑examination scores is ?=0.5.r=0.5. The pre‑exam totals for all students in the course have mean 280280 and standard deviation 40.40. The final‑exam scores have mean 7575 and standard deviation 8.8. Professor Krugman has lost Julie’s final exam but knows that her total before the exam was 300.300. He decides to predict her final‑exam score from her pre‑exam total. (a) Which of the choices is the least‑squares regression line of final‑exam scores on pre‑exam total scores in this course?
