b. The United Medical Agency is investigating the cost of maintaining the diabetic patients within its plan. These patients have typically been running up costs at the rate of $1,240 per month. A sample of 8 cases were observed and the costs are given below: Patient A B с D E F G H Costs 1260 1172 1181 1101 1103 1360 1281 1115 i. Calculate a 95% confidence interval for the mean cost. 11. 111. Comment on the hypothesis that the mean cost is greater than $1,240. Use the 5% level of significance. Include all steps. Comment on the hypothesis that the mean cost is equal to $1,240. Use the 10% level of significance. Include all steps.

A graduate student is interested in how viewing different types of scenes affects working memory. For his study, he selects a random sample of 36 adults. The subjects complete a series of working memory tests before and after walking in an urban setting. Before the walk, the mean score on the test of working memory was 9.1. After the walk, the mean score was 1.4 higher. The graduate student has no presupposed assumptions about how viewing different types of scenes affects working memory, so he formulates the null and alternative hypotheses as: H00 : μDD = 0 H11 : μDD ≠ 0 Assume that the data satisfy all of the required assumptions for a repeated-measures t test. The graduate student calculates the following statistics for his hypothesis test: Mean difference (MDD) 1.4 Estimated population standard deviation of the differences (s) 1.6 Estimated standard error of the mean differences (sMDMD) 0.2667 Degrees of freedom (df) 35 The t statistic 5.25 The critical values of t…

The accompanying data were read from a plot (and are a subset of the complete data set) given in an article. The data represent the mean response times for a group of individuals with closed-head injury (CHI) and a matched control group without head injury on 10 different tasks. Each observation was based on a different study, and used different subjects, so it is reasonable to assume that the observations are independent. y = Study 1 2 3 4 5 6 7 8 9 10 Mean Response Time CHI 302 492 658 684 922 1044 1421 1329 1481 1815 t = Control 250 360 475 (a) Fit a linear regression model that would allow you to predict the mean response time for those suffering a closed-head injury from the mean response time on the same task for individuals with no head injury. (Round your answers to four decimal places.) 525 610 740 880 920 1010 1200 (b) Do the sample data support the hypothesis that there is a useful linear relationship between the mean response time for individuals with no head injury and the…

Exhibit 2 The management of a department store is interested in estimating the difference between the mean credit purchase of customers using the stores credit card versus those customers using a national major credit card. You are given the following information:    STORES CARD MAJOR CREDIT CARD Sample Size  75 52 Sample Mean $185 $150 Sample Std Dev $12 $8 Q21a = Refer to Exhibit 2. A Point estimate for the difference between the mean purchases of the users of the two credit cards is: