3. An experiment was performed to compare the abrasive wear of twodifferent laminated materials. Twelve pieces of material 1 were tested byexposing each piece to a machine measuring wear. Ten pieces of material 2were similarly tested. In each case, the depth of wear was observed. Thesamples of material 1 gave an average (coded) wear of 85 units with asample standard deviation of 4, while the samples of material 2 gave anaverage of 81 with a sample standard deviation of 5. Can we conclude atthe 0.10 level of significance that the two unknown population variancesare equal? Assume the populations to be approximately normal.

The question is based on a hypo. testing Given : Total no. of pieces of material 1 ( n1 ) = 12…

Answered: 3. An experiment was performed to…

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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Bowker and Lieberman (1972) gave the results for tests of two thermostats used in irons that were made by an old supplier and a new supplier. 18 thermostats were sampled from the old supplier and 21 thermostats were sampled from the new supplier. The actual temperatures measured with a thermocouple and were recorded. The sample from the old supplier had a mean of x₁ =549.8 and a standard deviation of s₁=9.6. The sample from the new supplier had a mean of x₂=550.4 and a standard deviation of s2=11.2. Determine the value of the pooled standard deviation Sp Sp = ... (Record to two decimal places.) 4
In a study of the invasive species heracleum mantegazzium, Jan Pergl and associates compared the density of these plants in their native area in Russia and in an invaded area of the Czech Republic. In their native area, the average density was well-established as μ = 5 plants per square meter. In an invaded area, a sample of n = 60 plants produced an average density of x = 11.117 plants per square meter with a sample standard deviation of s = 2.37 plants per square meter. Using a signficance level of α = 0.01, is there sufficient evidence to conclude that the density of the species in the invasive area is significantly higher than in the native area? Use the hypothesis-testing framework to answer this question. Be sure to state both the null and alternative hypothesis, calculate a test statistic, and state the conclusion in non-technical terms. You may use either the P-value or critical value method, but make sure to state which method you use.
A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVs equipped with the tires. The mean braking distance for SUVS equipped with tires made with compound 1 is 68 feet, with a population standard deviation of 13.9. The mean braking distance for SUVs equipped with tires made with compound 2 is 73 feet, with a population standard deviation of 13.7. Suppose that a sample of 72 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVS equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let μ, be the true mean braking distance corresponding to compound 1 and μ₂ be the true mean braking distance corresponding to compound 2. Use the 0.05 level of significance. Step 1 of 5: State the null and alternative hypotheses for the test.
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
The slant shear test is widely accepted for evaluating the bond of resinous repair materials to concrete; it utilizes cylinder specimens made of two identical halves bonded at 30°. An article reported that for 12 specimens prepared using wire-brushing, the sample mean shear strength (N/mm2) and sample standard deviation were 18.60 and 1.56, respectively, whereas for 12 hand-chiseled specimens, the corresponding values were 23.19 and 4.07. Does the true average strength appear to be different for the two methods of surface preparation? State and test the relevant hypotheses using a significance level of 0.05. (Use ?1 for wire-brushing and ?2 for hand-chiseling.) H0: ?1 − ?2 = 0Ha: ?1 − ?2 ≤ 0H0: ?1 − ?2 = 0Ha: ?1 − ?2 < 0 H0: ?1 − ?2 = 0Ha: ?1 − ?2 > 0H0: ?1 − ?2 = 0Ha: ?1 − ?2 ≠ 0 Calculate the test statistic and determine the P-value. (Round your test statistic to one decimal place and your P-value to three decimal places.) t = P-value = You may have computed…
Only need help with finding tcalc.
2. Traces of toxic, man-made hexachlorohexanes in North Sea sediments were extracted by a known process and by two new procedures, and measured by chromatography. Method Concentration found Conventional Procedure A (pg/g) 34.4 42.9 Standard deviation (pg/g) 3.6 1.2 Number of replications 6 6 a.) Is the standard deviation for procedure A significantly different from that of the conventional procedure at 95% confidence level? b.) Is the mean concentration found by procedure A significantly different from that of the conventional procedure at 95% confidence level?
A scientist interested in monitoring chemical contaminants in food, and thereby the accumulation of contaminants in human diets, selected a random sample of 25 male adults. From this sample, it was found that the average daily intake of dairy products was 756 grams per day with a standard deviation of 35 grams per day. Use this sample information to construct a 95% confide
A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances for SUVs equipped with the tires. The mean braking distance for SUVs equipped with tires made with compound 1 is 65 feet, with a population standard deviation of 13.6. The mean braking distance for SUVs equipped with tires made with compound 2 is 69 feet, with a population standard deviation of 8.5. Suppose that a sample of 55 braking tests are performed for each compound. Using these results, test the claim that the braking distance for SUVs equipped with tires using compound 1 is shorter than the braking distance when compound 2 is used. Let μ₁ be the true mean braking distance corresponding to compound 1 and μ₂ be the true mean braking distance corresponding to compound 2. Use the 0.05 level of significance. Step 5 of 5: State the conclusion of the hypothesis test. Answer Tables Keypad Keyboard Shortcuts Previous Step Answers There is sufficient evidence…

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