The flexural strengths of a random sample of 10 concrete beams were measured at 24 hours from one lotduring paving of a parking lot, showing a mean of 5.2 MPa and an estimated standard deviation of 0.47MPа.What is the estimated percentage of the population that has flexural strength less than the minimumspecified 24-hour strength of 4.5 MPa?If the specification says that there should not be more than a 5% probability that the flexural strengthis less than the minimum, does this lot pass?Is this sampling procedure sampling-by-attributes or sampling-by-variable?а.b.С.

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Answered: The flexural strengths of a random…

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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A random sample of 76 eighth grade students' scores on a national mathematics assessment test has a mean score of 267. This test result prompts a state school administrator to declare that the mean score for the state's eighth graders on this exam is more than 260. Assume that the population standard deviation is 33. At α=0.11, is there enough evidence to support theadministrator's claim? Complete parts (a) through (e).
Suppose the lengths of loaves of rye bread produced at a bakery are normally distributed with a mean length of 25 centimeters and a standard deviation of 4 centimeters. Find a 90th percentile for the loaf lengths. That is, find a value c so that there is a 90% chance that a randomly selected loaf has a length less than c and there is a 10% chance that a randomly selected loaf has a length greater than c.
The thickness of a plastic film (in mils) on a sub- strate material is thought to be influenced by the temperature at which the coating is applied. A completely randomized experiment is carried out. Eleven substrates are coated at 125°F, resulting in a sample mean coating thickness of = 103.5 and a sample standard deviation of s1 = 10.2. Another 13 substrates are coated at 150°F, for which , = 99.7 and s2 = 20.1 are observed. It was originally suspected that raising the process temperature would reduce mean coating thickness. Find a 99% confidence interval on the difference in mean coating thickness Hi - H2. Assume each population is normally distributed but that their variances are not equal. What is the lower bound? Two decimal places
A very large company is interested in its employees' productivity. The company reports from its historical data that its employees spend a mean of 164 minutes per employee (on a typical day) dealing with email. To test this claim, an independent consultant chooses 26 employees at random and finds that those employees spend a sample mean of 172 minutes dealing with email, with a sample standard deviation of 21 minutes. Assume that the population of amounts of time employees spend dealing with email is approximately normally distributed. Complete the parts below to perform a hypothesis test to see if there is enough evidence, at the 0.05 level of significance, to reject the claim that u, the mean number of minutes employees spend dealing with email, is equal to 164. (a) State the null hypothesis H, and the alternative hypothesis H, that you would use for the test. Ho: I H: OSO D=D (b) Perform at test and find the p-value. Here is some information to help you with your t test.
An oceanographer claims that the mean dive duration of a North Atlantic right whale is 11.4 minutes. A random sample of 35 dive durations has a mean of 12.4 minutes and a standard deviation of 2.1 minutes. At a = 0.05 is there enough evidence to reject the oceanographer's claim? Complete parts (a) through (d) below. Assume the population is normally distributed. (a) Identify the claim and state Ho and H3- Họ: H3: (Type integers or decimals. Do not round.) The claim is the hypothesis.
A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 749 hours. A random sample of 28 light bulbs has a mean life of 726 hours. Assume the population is normally distributed and the population standard deviation is 57 hours. At a = 0.02, do you have enough evidence to reject the manufacturer's claim? Complete parts (a) through (e). A. C. Fail to reject Ho - Fail to reject Ho Fail to reject Ho- Reject Ho- Reject Ho Reject H, Reject Ho- 4 (c) Identify the standardized test statistic. Use technology. (Round to two decimal places as needed.)
An 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 is
The quality-control manager at a compact fluorescent light bulb (CFL) factory needs to determine whether the mean life of a large shipment of CFLs is equal to 7,508 hours. The population standard deviation is 840 hours. A random sample of 49 light bulbs indicates a sample mean life of 7,328 hours. Let μ be the population mean. Determine the null hypothesis, H0, and the alternative hypothesis, H1.
An obstetrician read that a newborn baby loses on average 7 ounces in the first two days of his or her life. He feels that in the hospital where he works, the average weight loss of a newborn baby is less than 7 ounces. A random sample of 33 newborn babies has a mean weight loss of 6.2 ounces. The population standard deviation is 1.5 ounces. Is there enough evidence at =α0.01 to support his claim? Assume that the variable is normally distributed. Use the P -value method with tables. hello there are five parts to the question it asks to state the hypothessis and identify the claim it asks to compute the test value find the p value and choose the null hypothesis
An obstetrician read that a newborn baby loses on average 7 ounces in the first two days of his or her life. He feels that in the hospital where he works, the average weight loss of a newborn baby is less than 7 ounces. A random sample of 30 newborn babies has a mean weight loss of 6.4 ounces. The population standard deviation is 1.6 ounces. Is there enough evidence at =α0.01 to support his claim? Assume that the variable is normally distributed. Use the critical value method with tables. hello the question askas to find the critical value compute the test value and select the hypothesis
A researcher claims that the average life span of mice can be extended when the calories in their diet are reduced by approximately 40% from the time they are weaned. The restricted diets are enriched to normal levels by vitamins and protein. Suppose that a sample of 10 mice is fed a normal diet and has anaverage life span of 32.1 months with a standard deviation of 3.2 months, while a sample of 15 mice is fed the restricted diet and has an average life span of 37.6 months with a standard deviation of 2.8 months. Assume the distributions of life spans for the regular and restricted diets are approximately normal withequal variance.(a) State the appropriate hypotheses to test the researcher’s claim.(b) Conduct the test at the 0.05 level of significance. What do you conclude?
A UCLA researcher claims that the average life span of mice can be extended by as much as 8 months when the calories in their diet are reduced by approximately 40% from the time they are weaned. The restricted diets are enriched to normal levels by vitamins and protein. Suppose that a random sample of 10 mice is fed a normal diet and has an average life span of 32.1 months with a standard deviation of 3.2 months, while a random sample of 15 mice is fed the restricted diet and has an average life span of 37.6 months with a standard deviation of 2.8 months. Test the hypothesis, at the 0.05 level of significance, that the average life span of mice on this restricted diet is increased by 8 months against the alternative that the increase is less than 8 months. Assume the distributions of life spans for the regular and restricted diets are approximately normal with equal variances. Do not use t-test statistic.

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