A sample of 75 concrete blocks had a mean mass of 38.3 kg with a standard deviation of 0.5 kg.
An engineer claims that the mean mass is between 38.2 and 38.4 kg. With what level of confidence can this statement be made? (Express the final answer as a percent and round to two decimal places.)
The level of confidence is
A sample of 75 concrete blocks had a mean mass of 38.3 kg with a standard...
A new concrete mix is being designed to provide adequate compressive strength for concrete blocks. The specification for a particular application calls for the blocks to have a mean compressive strength μ greater than 1350 kPa. A sample of 100 blocks is produced and tested. Their mean compressive strength is 1356 kPa and their standard deviation is 70 kPa. A test is made of H0 : µ ≤ 1350 versus H1 : µ > 1350. a. Find the P-value. Round...
In a sample of 65 electric motors, the average efficiency (in percent) was 85 and the standard deviation was 2. a) Find a 98% lower confidence bound for the mean efficiency. Round the answer to two decimal places. b) The claim is made that the mean efficiency is greater than 84.615%. With what level of confidence can this statement be made? Express the answer as a percent and round to two decimal places.The level of confidence is ???????? %.
The capacities (in ampere-hours) were measured for a sample of 120 batteries. The average was 178 and the standard deviation was 15. a)Find a 95% confidence interval for the mean capacity of batteries produced by this method. Round the answers to three decimal places.The 95% confidence interval is? b) Find a 99% confidence interval for the mean capacity of batteries produced by this method. Round the answers to three decimal places.The 99% confidence interval is? c) An engineer claims that...
A random sample of 24 observations is used to estimate the population mean. The sample mean and the sample standard deviation are calculated as 128.4 and 26.80, respectively. Assume that the population is normally distributed. [You may find it useful to reference the t table.) a. Construct the 95% confidence interval for the population mean. (Round intermediate calculations to at least 4 decimal places. Round "t" value to 3 decimal places and final answers to 2 decimal places.) Confidence interval...
Let the following sample of 8 observations be drawn from a normal population with unknown mean and standard deviation: 24, 22, 14, 26, 28, 16, 20, 21. [You may find it useful to reference the t table.) a. Calculate the sample mean and the sample standard deviation (Round intermediate calculations to at least 4 decimal places. Round "Sample mean" to 3 decimal places and "Sample standard deviation" to 2 decimal places.) Answer is complete but not entirely correct. Sample mean...
Use the one-mean t-interval procedure with the sample mean, sample size, sample standard deviation, and confidence level given below to find a confidence interval for the mean of the population from which the sample was drawn. x̄=4.0 n=61 s=6.1 confidence level =99% The 99% confidence interval about μ is ??? to ??? (Round to four decimal places as needed.)
Let the following sample of 8 observations be drawn from a normal population with unknown mean and standard deviation: 21, 20, 25, 18, 28, 19, 13, 22. [You may find it useful to reference the t table.] a. Calculate the sample mean and the sample standard deviation. (Round intermediate calculations to at least 4 decimal places. Round "Sample mean" to 3 decimal places and "Sample standard deviation" to 2 decimal places.) b. Construct the 90% confidence interval for the population...
A random sample of 49 measurements from one population had a sample mean of 10, with sample standard deviation 3. An independent random sample of 64 measurements from a second population had a sample mean of 12, with sample standard deviation 4. Test the claim that the population means are different. Use level of significance 0.01. (c) Compute x1 − x2. x1 − x2 = Compute the corresponding sample distribution value. (Test the difference μ1 − μ2. Round your answer...
The mean of a population is 75 and the standard deviation is 14. The shape of the population is unknown. Determine the probability of each of the following occurring from this population. a. A random sample of size 33 yielding a sample mean of 79 or more b. A random sample of size 140 yielding a sample mean of between 73 and 77 c. A random sample of size 218 yielding a sample mean of less than 75.7 (Round all...
A sample of 24 observations is selected from a normal population where the sample standard deviation is 4.45. The sample mean is 16.45. a. Determine the standard error of the mean. (Round the final answer to 2 decimal places.) The standard error of the mean is. b. Determine the 90% confidence interval for the population mean. (Round the t-value to 3 decimal places. Round the final answers to 3 decimal places.) The 90% confidence interval for the population mean is...