1.8. Question 7 Marketing researchers have determined that there is a relationship between sales of canned tuna and the price of canned tuna. Specifically, SALES = 40, 710 - 430PRICE, where SALES are cans sold per week and PRICE is measured in cents per can. Suppose PRICE is (approximately) a normal random variable with mean μ = 75 cents and standard deviation σ 5 cents. That is PRICE~N(75, 25).\ (a) = (a) What is the expected value of SALES? (b) What is the variance of SALES? (c) Find the probability that more than 6, 300 cans are sold in a week. ↑↓孟曱 (b) (c)

Let x be a random variable that represents the pH of arterial plasma (i.e., acidity of the blood). For healthy adults, the mean of the x distribution is ? = 7.4.† A new drug for arthritis has been developed. However, it is thought that this drug may change blood pH. A random sample of 36 patients with arthritis took the drug for 3 months. Blood tests showed that x = 8.6 with sample standard deviation s = 3.0. Use a 5% level of significance to test the claim that the drug has changed (either way) the mean pH level of the blood. (A) What is the value of the sample test statistic? (Round your answer to three decimal places.) (B) Find the P-value. (Round your answer to four decimal places.)

In the year 2033, Sarai Patterson is a leading traveling nurse. Sarai is interested in reducing the mean recovery time for patients after experiencing a serious injury (assume recovery times are normally distributed). Suppose the mean recovery time is presently 8.6 months. Sarai takes a random sample of 46 patients that have experienced serious injury to participate in a new treatment program and finds the sample mean is 8.1 months and a sample standard deviation of 1.2 months. Using α = 0.05, answer the following questions. a) What is the setup for your null and alternative hypothesis? b) What is the value of the test statistic? c) What is/are the critical value(s)?

#2) A large warehouse installed a security system a few years ago. Under an older system the managers estimated that they were losing an average of $678 worth of goods to thieves each week. A random sample of 36 weekly records under the current system showed that they were still losing an average of $650 worth of goods each week. The sample standard deviation was s = $93. Does this indicate that the average loss is different (either more or less) than the previous $678 per week? Use a 5% level of significance.

2. A pet association claims that the mean annual costs of food for dogs and cats are the same. The results for samples of the two types of pets are shown in the following table. On wished to test the claim. Assume both populations follow normal distributions Dogs Cats 21 - 16 T1= 239 n2 = 18 Iz= 203 S1 = 32 82 =28 with equal variances. Which of the following formula should be used to calculate the standardized test statistic? (a) Z = (21-32)- Do lu A n2 = (E1-2)-Do (b) Z V n1+2 (c) T (1-2)-Do (21-1)a7+(n2-1)s I1 11+11タ-3 V 1'n2 (d) T = d- Do sp/Vn (e) Z

18.  A set of n = 52 pairs of scores (X and Y values) in a research study has a Pearson correlation of r = -0.7. What percentage of the variance for the Y scores is predicted by its relationship with X?

Let x be a random variable that represents the pH of arterial plasma (i.e., acidity of the blood). For healthy adults, the mean of the x distribution is ? = 7.4.† A new drug for arthritis has been developed. However, it is thought that this drug may change blood pH. A random sample of 36 patients with arthritis took the drug for 3 months. Blood tests showed that x = 8.6 with sample standard deviation s = 3.5. Use a 5% level of significance to test the claim that the drug has changed (either way) the mean pH level of the blood. What is the level of significance?