Three experiments investigating the relation between need for cognitive closure and persuasion were performed. Part of the study involved administering a "need for closure scale" to a group of students enrolled in an introductory psychology course. The "need for closure scale" has scores ranging from 101 to 201. For the 66 students in the highest quartile of the distribution, the mean score was x = 177.10. Assume a population standard deviation of a = 7.85. These students were all classified as high on their need for closure. Assume that the 66 students represent a random sample of all students who are classified as high on their need for closure. How large a sample is needed if we wish to be 99% confident that the sample mean score is within 2.0 points of the population mean score for students who are high on the need for closure? (Round your answer up to the nearest whole number.) A USE SALT students

A researcher thinks that people under forty have vocabularies different from those over sixty years of age. The researcher administers a vocabulary test to a group of 50 younger subjects and a group of 50 older subjects. Higher scores reflect better performance. The mean score for younger subjects was 9.0, and the standard deviation of younger subject's scores was 5.0. The mean score for older subjects was 20.0, and the standard deviation of older subject's scores was 8.0. Does this experiment provide evidence for the researcher's theory? As part of your answer: a. Please provide, in words, the null and alternative hypotheses (NO symbols). Note that you can choose whether to perform a one- or two-tailed test Answer:  Null hypothesis: Alernative hypothesis:   b. Provide a brief (one or two sentence(s) rationale for your decision to use a one or two tailed test Answer   c. Calculate the Standard Error (SE) of the mean difference (demonstrate calculation steps to get an entire point) and…

A pharmaceutical company needs to know if its new cholesterol drug, Praxor, is effective at lowering cholesterol levels. It believes that people who take Praxor will average a greater decrease in cholesterol level than people taking a placebo. After the experiment is complete, the researchers find that the 38 participants in the treatment group lowered their cholesterol levels by a mean of 23.2 points with a standard deviation of 4.4 points. The 44 participants in the control group lowered their cholesterol levels by a mean of 21.5 points with a standard deviation of 2.9 points. Assume that the population variances are not equal and test the company's claim at the 0.01 level. Let the treatment group be Population 1 and let the control group be Population 2. Step 2 of 3: Compute the value of the test statistic. Round your answer to three decimal places.

Three experiments investigating the relation between need for cognitive closure and persuasion were performed. Part of the study involved administering a "need for closure scale" to a group of students enrolled in an introductory psychology course. The "need for closure scale" has scores ranging from 101 to 201. For the 66 students in the highest quartile of the distribution, the mean score was x = 177.10. Assume a population standard deviation of o = 8.27. These students were all classified as high on their need for closure. Assume that the 66 students represent a random sample of all students who are classified as high on their need for closure. How large a sample is needed if we wish to be 99% confident that the sample mean score is within 1.8 points of the population mean score for students who are high on the need for closure? (Round your answer up to the nearest whole number.) n USE SALT students