A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVs equipped with the tires. The
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- A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVS equipped with the tires. SUVS equipped with tires using compound 1 have a mean braking distance of 43 feet and a standard deviation of 6.6 feet. SUVS equipped with tires using compound 2 have a mean braking distance of 50 feet and a standard deviation of 11.8 feet. Suppose that a sample of 61 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVS equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let ui be the true mean braking distance corresponding to compound 1 and uz be the true mean braking distance corresponding to compound 2. Use the 0.01 level of significance. Step 3 of 4: Determine the decision rule for rejecting the null hypothesis Ho. Round the numerical portion of your answer to two decimal places. E Keypad Keyboard Shortcuts…arrow_forwardA researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVs equipped with the tires. The mean braking distance for SUVs equipped with tires made with compound 1 is 72 feet, with a population standard deviation of 10.6. The mean braking distance for SUVS equipped with tires made with compound 2 is 74 feet, with a population standard deviation of 12.3. Suppose that a sample of 38 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVs equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let μ₁ be the true mean braking distance corresponding to compound 1 and ₂ be the true mean braking distance corresponding to compound 2. Use the 0.05 level of significance. Step 3 of 5: Find the p-value associated with the test statistic. Round your answer to four decimal places.arrow_forwardA physical therapist wanted to know whether the mean step pulse of men was less than the mean step pulse of women. She randomly selected 54 men and 70 women to participate in the study. Each subject was required to step up and down a 6-inch platform. The pulse of each subject was then recorded. The following results were obtained. Two sample T for Men vs Women N Mean StDev SE Mean Men Women 98% CI for mu Men - mu Women (- 12.20, - 1.00) T-Test mu Men = mu Women (vs H2 O C. Ho: H1 = H2; Ha: H1 #H2 (b) Identify the P-value and state the researcher's conclusion if the level of significance was a = 0.01. What is the P-value? P-value =arrow_forward
- A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVS equipped with the tires. The mean braking distance for SUVs equipped with tires made with compound 1 is 71 feet, with a population standard deviation of 11.0. The mean braking distance for SUVs equipped with tires made with compound 2 is 74 feet, with a population standard deviation of 12.3. Suppose that a sample of 70 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVS equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let μ₁ be the true mean braking distance corresponding to compound 1 and μ₂ be the true mean braking distance corresponding to compound 2. Use the 0.05 level of significance. Step 2 of 5: Compute the value of the test statistic. Round your answer to two decimal places. Answer How to enter your answer (opens in new window)…arrow_forwardA study was conducted by a group of neurosurgeons. They compared a dynamic system (Z-plate) and a static system (ALPS plate) in terms of the number of acute postoperative days in the hospital spent by the patients. The descriptive statistics for these data are as follows: for 14 patients with dynamic system, the sample mean number of acute postoperative days was 7.36 with standard deviation of 1.22; for 6 patients with static system the sample mean number of acute postoperative days was 10.5 with sample standard deviation of 4.59. Assume that the numbers of acute postoperative days in both populations are normally distributed. We wish to estimate µ1 − µ2 with a 99 percent confidence interval. Can you assume unknown population variance are equal. a. Degrees of freedom and t-value are b. Margin of error and confidence interval are c. Based on your interval in part (b), we can state with 99 percent confidence that the average numbers of acute postoperative days in two populations i.…arrow_forwardAn electrical engineer wishes to compare the mean lifetimes of two types of transistors in an application involving high-temperature performance. A sample of 60 transistors of type A were tested and were found to have a mean lifetime of 1827 hours and a standard deviation of 174 hours. A sample of 180 transistors of type B were tested and were found to have a mean lifetime of 1658 hours and a standard deviation of 231 hours. Let ux represent the population mean for transistors of type A and µy represent the population mean for transistors of type B. Find a 95% confidence interval for the difference uy – µy . Round the answers to three decimal places. The 95% confidence interval isarrow_forward
- A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVs equipped with the tires. The mean braking distance for SUVs equipped with tires made with compound 1 is 65 feet, with a population standard deviation of 13.6. The mean braking distance for SUVS equipped with tires made with compound 2 is 69 feet, with a population standard deviation of 8.5. Suppose that a sample of 55 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVs equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let μ₁ be the true mean braking distance corresponding to compound 1 and μ₂ be the true mean braking distance corresponding to compound 2. Use the 0.05 level of significance. Step 3 of 5 Find the p-value associated with the test statistic. Round your answer to four decimal places. Answer How to enter your answer (opens in…arrow_forwardIn a class of twenty-five 15-year old girls the average height is M = 62.60 inches. The national average for girls at this age is reported as follows: µ = 63.80 inches with a standard deviation, s = 2.66 inches. 1. What is the effect size Cohen’s d and what does it tell us about the effect? 2. Compute the z-statistic.arrow_forwardSuppose that weights of college mathematics textbooks in the United States are normally distributed with mean µ = 2.25 lbs and variance σ2 = 0.2025 lbs. Find the weight that corresponds to Q3 and interpret this measure of position in the context of the problem.arrow_forward
- A study is being conducted to compare vitamin C and zinc to determine which is better at fighting colds. Customers believe vitamin C is better at fighting colds. What are the appropriate hypotheses for this testing scenario? Let μc equal the mean of the effectiveness of vitamin C and μz equal the mean of the effectiveness of zinc. O Ho: Hc - Hz= 0 Ha Hc - Hz > 0 O Ho: Hc - Hz= 0 Ha Mc-Hz 0 o Ho: Xe – xz = 0 Hai Xi — Xz #0arrow_forwardA researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVs equipped with the tires. The mean braking distance for SUVS equipped with tires made with compound 1 is 68 feet, with a population standard deviation of 13.9. The mean braking distance for SUVs equipped with tires made with compound 2 is 73 feet, with a population standard deviation of 13.7. Suppose that a sample of 72 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVS equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let μ, be the true mean braking distance corresponding to compound 1 and μ₂ be the true mean braking distance corresponding to compound 2. Use the 0.05 level of significance. Step 1 of 5: State the null and alternative hypotheses for the test.arrow_forwardTwo different formulas of an oxygenated motor fuel are being tested to study their road octane numbers. The variance of road octane number for formula 1 is o? 1.5, and for formula 2 it is o, = 1.2. Two random samples of size n1 15and n2 20 are tested, and the mean octane numbers observed are x 89.5 fluid ounces and X2 93.1 fluid ounces. Assume normality. (a) Test the hypotheses Ho : µ1 = H2 versus Hị :µ1 < µz using a = 0.05. Round your answer to three decimal places (e.g. 98.765). Zo = Но- (b) Calculate a 95% two-sided confidence interval on the mean difference road octane number, x1 – X2. Round your answer to three decimal places (e.g. 98.765). < H1 - H2 < (c) What sample size would be required in each population if you wanted to be 95% confident that the error in estimating the difference in mean road octane number is less than 1? ni = n2 = i . Round your answer up to the nearest integer.arrow_forward
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