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- Rachael got a 660 on the analytical portion of the Graduate Record Exam (GRE). If GRE scores are normally distributed and have mean μ = 600 and standard deviation σ = 30, what is her standardized score?Two independent laboratories have produced drugs that provide relief to arthritis and the results is shown below. At 5% level of significant, can we conclude that the drug produced by laboratory A significantly causes a shorter period of relief (in Hours) than that of a drug produced by laboratory B? Laboratory Sample Mean Standard Deviation A 75 4.5 2.5 B 60 5.5 2.0The diameter of a spindle in a small motor is supposed to be 4.4 millimeters (mm) with a standard deviation of 0.11 mm. If the spindle is either too small or too large, the motor will not work properly. The manufacturer measures the diameter in a sample of 15 spindles to determine whether the mean diameter has moved away from the required measurement. Suppose the sample has an average diameter of 4.27 mm. H0: Ha: (b) Harry thinks that prices in Caldwell are lower than the rest of the country. He reads that the nationwide average price of a certain brand of laundry detergent is $20.95 with standard deviation $0.78. He takes a sample from 5 local Caldwell stores and finds the average price for this same brand of detergent is $18.31. H0: Ha:
- A researcher is interested in learning about average online hours per day for Camosun College students. Data is gathered from 50 students - mean online hours is 7.52 with a standard deviation of 2.85. Calculate the 95% CI (or alpha at 0.05) and interpret your results in a full sentence. Now calculate a 99% CI for the above. How does your answer change? If the researcher sampled a group of 24 students and the new calculated mean and standard deviation are the same as with the larger group of 50, would the 99% CI change from b above? If yes, in what way?webassign.net The Toylot company makes an electric train with a motor that it claims will draw an average of only 0.8 ampere (A) under a normal load. A sample of nine motors was tested, and it was found that the mean current was x = 1.32 A, with a sample standard deviation of s = 0.43 A. Do the data indicate that the Toylot claim of 0.8 A is too low? (Use a 1% level of significance.) What are we testing in this problem? O single proportion O single mean (a) What is the level of significance? State the null and alternate hypotheses. O Ho: H # 0.8; H1: µµ = 0.8 Ο H0: μ = 0.8; H1: μ+ 0.8 O Ho: p = 0.8; H1: p > 0.8 O Ho: p + 0.8; H1: p = 0.8 O Ho: p = 0.8; H1: p + 0.8 O Ho: H = 0.8; H1: µ > 0.8 (b) What sampling distribution will you use? What assumptions are you making? O The Student's t, since we assume that x has a normal distribution with known o. O The standard normal, since we assume that x has a normal distribution with known ơ. O The Student's t, since we assume that x has a normal…The president of a college wants to determine the mean number of units that college students take per semester. How large of a sample is required in order to be 99% sure that a sample mean will be off by no more than 1.25 units? An initial study suggested that the standard deviation is approximately 2.1 units.
- Based on data from a college, scores on a certain test are normally distributed with a mean of 1531 and a standard deviation of 324. Complete parts below. c. Find the percentage of scores between 1369 and 1661.The mean volume of a large population of vials used to be 10.9 ml. To test whether this value has decreased, a random sample of size 300 vials are measured and found to have a sample mean of 10.5 ml. We will assume that the population of vial volumes is normally distributed with standard deviation of 3.6 ml. Test whether the mean population volume has decreased at a level of significance of 1%. Show your relevant steps below. Step 1: Hypotheses: • The null hypothesis Ho is (choose one): µ = 10.9 X = 10.5 x = 10.9 u = 10.5 • For the alternative hypothesis Ha we change the equal sign in Ho to (choose one):The mean diameter of a ball bearing produced by a certain manufacturer is 0.60 cm with a standard deviation of 0.04 cm. A sample of 25 ball bearings is randomly selected from a production run. The sample had a mean of 0.60008 and a median 0.60333. What is the standard error for the sample mean? O A. 0.00032 O B. 0.008 O C. 0.0016 O D. 0.00008 O E. 0.00333
- The monthly income from a particular occupation is normally distributed, with a mean of 5000 dollars and a standard deviation of 250 dollars.Find the monthly income that 15% of people at the occupation makes less than.Round your answer to the nearest cent.A random sample of 100,000 credit sales in a department store showed an average sale of $87.25. From past data, it is known that the standard deviation of the population is $20.00. What is the standard error of the mean? (Round to the 4 decimal places)
