5. A civil engineering firm is conducting a study on the compressive strength of a new type ofconcrete mix designed for rapid construction projects. A random sample of 30 specimens of thenew concrete mix is tested for compressive strength after curing for 28 days. The sample has anaverage compressive strength of 35 MPa (megapascals) with a standard deviation of 5 MPa.a. Calculate 90% confidence interval (CI) for the population mean μ. Write down yourinterpretation.b. Calculate 95% CI for the population mean μ. Write down your interpretation.c. Calculate 99% CI for the population mean u. Write down your interpretation.d. Explain why the size of CI changed between parts a - c.Assume the compressive strength of concrete specimens follows a normal distribution.

Let X be the compressive strength of the concrete specimen.The sample mean and sample standard…

Answered: 5. A civil engineering firm is…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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A steel pipe company recently developed a new pipe product for a customer. According to specifications, the pipe is supposed to have an average outside diameter of 2.00 inches with a standard deviation equal to 0.10 inches, and the distribution of outside diameters is to be normally distributed. Before going into full-scale production, the company selected a random sample of 30 sections of pipe from the initial test run, as shown in the accompanying table. Complete parts a and b below. (Data are shown in images)
The time it takes for a compact fluorescent bulb to reach full brightness is normally distributed with mean 29.9 seconds and standard deviation 4.1 seconds. Find and interpret the z-score for x = 26.4.
The mean pulse rate for adult males is approximately 61.4 beats per minute. In a sample of 27 overweight males, the mean pulse rate was 62.1 beats per minute with a standard deviation of 4.19 beats per minute. Test at a = 0.10 whether these findings suggest that the mean pulse rate for all such overweight males is significantly greater than 61.4. You obtain a sample of size 27 with a mean of 62.1 and a standard deviation of 4.19. You believe that the population is normally distributed. (a). The null and alternative hypotheses are O Ho: ữ = 62.1 Ha:ữ > 62.1 Ho:µ = 61.4 Ha: µ > 61.4 Ο H0: μ = 61.4 На:р 62.1 Part 2 of 4 (b). The test statistic is (use 4 decimal places)
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
A manufacturer bonds a plastic coating to a metal surface. A random sample of nine observations on the thickness of this coating is taken from a week's output and the thickness (in millimeters) of these observations are shown below. Assuming normality, find a 90 % confidence interval for the population variance. 19.7 20.5 Click the icon to view a table of lower critical values for the chi-square distribution. Click the icon to view a table of upper critical values for the chi-square distribution. 21.8 18.2 Find the 90% confidence interval. 0<²0 (Round to four decimal places as needed.) 21.6 SCIOD 19.3 19.7 20.2 20.7
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 company that makes cola drinks states that the mean caffeine content per 12-ounce bottle of cola 40 milligrams. You want to test this claim. During your tests, you find that a random sample of thirty 12-ounce bottles of cola has a mean caffeine content of 39.2 milligrams. Assume the population is normally distributed with a standard deviation of 7.5 milligrams. At α=0.01, can you reject the company’s claim?
"The mean value of the design load on a foundation element is 6,000 kN, and its standard deviation is 1,200 kN. The estimated mean value of the bearing capacity is 12,000 kN, and its standard deviation 3,000 kN. If both the load and the resistance are Normally distributed, compute (a) the value of the reliability index B and (b) the probability of failure.", if the load and the resistance are positively correlated with p = 0.5.
The braking ability was compared for two car models. Random samples of two cars were selected. The first random sample of size 64 cars yield a mean of 36 and a standard deviation of 8. The second sample of size 64 yield a sample mean of 33 and a standard deviation of 8. Do the data provide sufficient evidence to indicate a difference between the mean stopping distances for the two models? Use Alpha= 0.01. Ho: µ1 – µ2 = 0 vs. Ha: µ1 – µ2 + 0 .p-value = 0.0017. Reject Ho Но: Д, — м2 — 0 vs. Ha:M1 — M2 + 0. p-value — 0.034. Ассеpt Ho O Ho:µ1 – Hz Но: И — 2 — 0 vs. Ha:M, — нz + 0. p-value —D 0.0017. Ассept Ho Ho: H1 – U2 = 0 vs. Ha: µ1 – µ2 + 0. p-value = 0.034. Reject Ho

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