Before playing the action video game, the mean score in their accuracy on the spatial task was 0.42. After playing the action video game, the mean score was -0.08. The mean of the differences between each person's pre- and postscores was 0.5, with a standard deviation of the differences equal to 2.4. The graduate student has no presupposed assumptions about whether playing video games increases peripheral visual perception abilities or decreases attention to peripheral regions because of focus on the gaming zone, so she formulates the null and alternative hypotheses as: Ho. HD =0 Hg: HD +0 She uses a repeated-measures t test. Because the sample size is large, if the null hypothesis is true as an equality, the test statistic follows a t- distribution with degree of freedom - This is a test. From the table we find that the critical score(s) for the level of significance a - .01 is In order to calculate the test statistic t, you will need to calculate the estimated standard error first, which is v The calculated test statistic is therefore t=

It seems these days that college graduates who are employed full-time work more than 40-hour weeks. Data are available that can help us decide if this is true. A survey was recently sent to a group of adults selected at random. There were 15 respondents who were college graduates employed full-time. The mean number of hours worked per week by these 15 respondents was 43 hours, with a standard deviation of 8 hours. Assume that the population of hours worked per week by college graduates employed full-time is normally distributed with mean μ. Can we conclude that μ is greater than 40 hours? Use the 0.05 level of significance. State the null hypothesis  H0  and the alternative hypothesis  H1 Find the t-test df & Solve the t-test value  Find the critical value Can we conclude, at the 0.05 level of significance, that the mean number of hours worked per week by college graduates is greater than 40 hours? Yes or No?

A psychology student conducted a study on using a chief executive​ officer's facial structure to predict a​ firm's financial performance. The facial​ width-to-height ratio​ (WHR) for each in a sample of 47 CEOs at publicly traded firms was determined. The sample resulted in x=2.23 and s=0.35. The student wants to predict the financial performance of a firm based on the value of the true mean facial WHR of CEOs. The student wants to use the value of μ=2.1. Do you recommend he use this​ value? Conduct a test of hypothesis for μ to help you answer the question. Specify all the elements of the​ test, including H0​, Ha​, test​ statistic, p-value, and your conclusion. Test at α=0.01.

What percent of the students received a score below 64, if the mean grade on a test was 70 and the standard deviation was 6. For the same test results as prob 1), what percent of studen ts scored between 64 and 80 .