A rods manufacturer makes rods with a length that is supposed to be 15 inches. A quality control technician sampled 31 rods and found that the sample mean length was 15.09 inches and the sample standard deviation was 0.19 inches. The technician claims that the mean rod length is less than 15 inches. What type of hypothesis test should be performed?________ select (left-tailed z-test,left-tailed t-test,two-tailed t-test,right-tailed t-test) What is the test statistic?______ What is the number of degrees of freedom?______

The number of chocolate chips in a popular brand of cookie is normally distributed with a mean of 19 chocolate chips per cookie and a standard deviation of 3.5 chips. When the cookies come out of the oven, only the middle 90% in terms of the number of chocolate chips are acceptable (the rest are considered defective). What are the cutoff numbers for the number of chocolate chips in acceptable cookies? (Give your answers to three decimal places)______    and _______

A clinical researcher performs a clinical trial on 12 patients to determine whether a drug treatment has an effect on serum glucose. The sample mean glucose of the patients before and after the treatment are summarized in the following table. The sample standard deviation of the differences was 6.   Sample mean glucose (mg/dL) Before treatment 114 After treatment 108 What type of hypothesis test should be performed?Select: Left-tailed z-test Unpaired t-test Two-tailed z-test Paired t-test    What is the test statistic?   What is the number of degrees of freedom?   Does sufficient evidence exist to support the claim that the drug treatment has an effect on serum glucose at the α=0.05 significance level? Select: _____Yes  OR  _____No

purses Researchers conducted an experiment to test the effects of alcohol. Erors were recorded in a test of visual and motor skills for a treatment group of 21 people who drank ethanol and another group of 21 people given a placebo. The errors for the treatment group have a standard deviation of 2.10, and the errors for the placebo group have a standard deviation of 0.71. Use a 0.05 significance level to test the claim that the treatment group has errors that vary significantly more than the errors of the placebo group. Assume that the two populations are normally distributed. se Hom bus What are the null and alternative hypotheses? ndar O A. Ho: o =0 O B. Ho: of +o? ntation OC. Ho o =0 OD. Hoi o? =o} book puncem Identify the test statistic. (Round to two decimal places as needed.) gnments Use technology to identify the P-value. dy Plan (Round to three decimal places as needed.) debook What is the conclusion for this hypothesis test? O A. Reject Ho. There is sufficient evidence to…

1 Jump to level 1 A pipes manufacturer makes pipes with a length that is supposed to be 11 inches. A quality control technician sampled 32 pipes and found that the sample mean length was 11.09 inches and the sample standard deviation was 0.2 inches. The technician claims that the mean pipe length is not 11 inches. What type of hypothesis test should be performed? Select What is the test statistic? Ex: 0.123 What is the number of degrees of freedom? Ex: 20 Does sufficient evidence exist at the a= 0.05 significance level to support the technician's claim? Select Check HIN 60°F

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A machine makes catheters for use in heart tests. The machine is designed so that the mean diameter of the catheter it makes can change but the standard deviation can't. The population standard deviation is .05 mm. Right now the machine is supposed to be making catheters with a mean diameter of 2 mm. During production an inspector checks the diameter of catheters to see if the machine has slipped out of the adjustment. A random sample of 50 catheters is taken. If the mean diameter for the sample is 2.04 mm, does this indicate the machine has slipped out of adjustment and the population average diameter of the catheter is no longer 2mm. The best test to use in this situation is a

A pipes manufacturer makes pipes with a length that is supposed to be 12 inches. A quality control technician sampled 35 pipes and found that the sample mean length was 12.05 inches and the sample standard deviation was 0.13 inches. The technician claims that the mean pipe length is not 12 inches. What type of hypothesis test should be performed? Two-tailed t-test Two-tailed z-test Left tailed t-test Left tailed z-test What is the test statistic? What is the number of degrees of freedom? Does sufficient evidence exist at the α=0.01 significance level to support the technician's claim? Yes or No

Low-fat or low-carb? Are low-fat diets more effective for weight loss? A sample of 46 subjects went on a low carbohydrate diet for six months. At the end of that time, the sample mean weight loss was 4.6 kilograms with a sample standard deviation of 6.28 kilograms. A second sample of 49 subjects went on a low-fat diet. Their sample mean weight loss was 2.3 kilograms with a standard deviation of 4.66 kilograms. Can you conclude that the mean weight loss differs between the two diets? Let μ1 denote the mean weight lost on the low-carb diet and μ2 denote the mean weight lost on the low-fat diet. Use the =α0.01level and the P-value method.   Compute the test statistic. Round the answer to three decimal places. t =

Good credit: The Fair Isaac Corporation (FICO) credit score is used by banks and other lenders to determine whether someone is a good credit risk. Scores range from 300 to 850, with a score of 720 or more indicating that a person is a very good credit risk. An economist wants to determine whether the mean FICO score is more than the cutoff of 720. She finds that a random sample of 85 people had a mean FICO score of 750 with a standard deviation of 95. Can the economist conclude that the mean FICO score is greater than 720? Use the α = 0.05 level of significance and the P-value method and Excel. (a) State the appropriate null and alternate hypotheses. Ho: H₁: This hypothesis test is a (Choose one) test. left tailed right-tailed two tailed