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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Listed in the data table are amounts of strontium-90 (in millibrcquerels or mBq, per gram of calcium) in a simple random sample of baby teeth obtained from residents in two cities. Assume that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal. Use a 0.10 significance level to test the claim that the mean amount of strontium-90 from city #1 residents is greater than the mean amount from city #2 residents. Find the test statistic, p value, and confidence interval
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.
A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 754 hours. A random sample of 30 light bulbs has a mean life of 732 hours. Assume the population is normally distributed and the population standard deviation is 62 hours. At a = 0.05, do you have enough evidence to reject the manufacturer's claim? Complete parts (a) through (e). Zo = - 1.65 (Use a comma to separate answers as needed. Round to two decimal places as needed.) Identify the rejection region(s). Choose the correct answer below. O A. B. O C. Fail to reject H- Fail to reject Ho Fail to reject Ho- Reject Ho Reject Ho Reject Ho Reject H,- -4
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.)
A manufacturer claims that the mean lifetime, u, of its light bulbs is 44 months. The standard deviation of these lifetimes is 7 months. Twenty-three bulbs are selected at random, and their mean lifetime is found to be 48 months. Assume that the population is normally distributed. Can we conclude, at the 0.01 level of significance, that the mean lifetime of light bulbs made by this manufacturer differs from 44 months? Perform a two-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places, and round your responses as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis H, and the alternative hypothesis H,. p H, :0 H, :0 (b) Determine the type of test statistic to use. (Choose one) v O=0 OSO |(c) Find the value of the test statistic. (Round to three or more decimal places.) O
A magazine conducts an annual survey in which readers rate their favorite cruise ship. All ships are rated on a 100-point scale, with higher values indicating better service. A sample of 38 ships that carry fewer than 500 passengers resulted in an average rating of 85.62, and a sample of 44 ships that carry 500 or more passengers provided an average rating of 81.10. Assume that the population standard deviation is 4.55 for ships that carry fewer than 500 passengers and 3.97 for ships that carry 500 or more passengers. (a) What is the point estimate of the difference between the population mean rating for ships that carry fewer than 500 passengers and the population mean rating for ships that carry 500 or more passengers? (Use smaller cruise ships − larger cruise ships.) (b) At 95% confidence, what is the margin of error? (Round your answer to two decimal places.) (c) What is a 95% confidence interval estimate of the difference between the population mean ratings for the…
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?

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