On the basis of extensive tests, the yield point of a particular type of mild steel-reinforcing bar is known to be normally distributed with = 100. The composition of the bar has been slightly modified, but the modification is not believed to have affected either the normality or the value of 0.(a) Assuming this to be the case, if a sample of 25 modified bars resulted in a sample average yield point of 8435 lb, compute a 90% CI for the true average yield point of the modified bar. (Round your answers to one decimal place.)(b) How would you modify the interval in part (a) to obtain a confidence level of 92%? (Round your answer to two decimal places.)The value of z✔ should be changed to

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Answered: On the basis of extensive tests, the…

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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In a manufacturing industry, the amounts which go into raw materials (Scraps) are supposed to be normally distributed with mean GHC 36. and standard deviation GHC 0.1. Once every 30 minutes a scrap is selected from the production line, and its contents are noted precisely. If the amount of the scrap goes below GHC 35.8. or above GHC 36.2, then the scrap will be declared out of control. i)If the process shifts so that μ = GHC 37 and σ = GHC 0.4, find the probability that a scrap will be declared out of control
5 c.)
To compare the dry braking distances from 30 to 0 miles per hour for two makes of automobiles, a safety engineer conducts braking tests for 35 models of Make A and 35 models of Make B. The mean braking distance for Make A is 43 feet. Assume the population standard deviation is 4.6 feet. The mean braking distance for Make B is 46 feet. Assume the population standard deviation is 4.5 feet. At α=0.10, can the engineer support the claim that the mean braking distances are different for the two makes of automobiles? Assume the samples are random and independent, and the populations are normally distributed. The critical value(s) is/are Find the standardized test statistic z for μ1−μ2.
Is there a relationship between (X) rate of poverty (measured as a percent of population below poverty level) and (Y) rates of teen pregnancy (measured per 1,000 females aged 15 to 17)? A researcher selected random states and collected the following data. The correlation coefficient between was 0.98. Determine whether the correlation is significant. Use the correlation test statistics. Compute the appropriate test statistics. The degree of freedom is 6 and alpha at 0.05.
3) For a sample of 306 students in a basic business communications course, the sample regression line y = 58.813 + 0.2875x was obtained. Here y = final student score at the end of the course x = score on a diagnostic writing skills test given at the beginning of the course The coefficient of determination was 0.1158 and the estimated standard deviation of the estimator of the slope of population regression line was 0.04566. a) Define and interpret the estimates of the regression equation. b) Interpret the coefficient of determination. c) What will happen to the final student score if his diagnostic writing test score increases by 2? d) How can you inmprove this model?
Assume that the helium porosity (in percentage) of coal samples taken from anyparticular seam is normally distributed with true population variance 0.36.(a) Compute a 95% two-sided CI for the true average porosity of a certain seam if the average porosity for 20 specimens from the seam was 4.85. (b) How large a sample size is necessary if the width of the 95% two-sided CI is to be 0.5? (c) Compute a 98% upper one-sided CI for true average porosity of another seam based on 16 specimens with a sample average porosity of 4.56.show major intermediate steps.
The desired percentage of SiO₂ in a certain type of aluminous cement is 5.5. To test whether the true average percentage is 5.5 for a particular production facility, 16 independently obtained samples are analyzed. Suppose that the percentage of SiO₂ in a sample is normally distributed with = 0.32 and that x = 5.23. (Use a = 0.05.) (a) Does this indicate conclusively that the true average percentage differs from 5.5? State the appropriate null and alternative hypotheses. O Ho: μ = 5.5 H₂:μ> 5.5 O Ho: μ = 5.5 H₂: μ = 5.5 ⒸHO: μ = 5.5 H₂:μ ≥ 5.5 O Ho: μ = 5.5 H₂: μ< 5.5 Calculate the test statistic and determine the P-value. (Round your test statistic to two decimal places and your P-value to four decimal places.) Z = P-value = State the conclusion in the problem context. O Do not reject the null hypothesis. There is not sufficient evidence to conclude that the true verage percentage differs from the desired percentage. O Reject the null hypothesis. There is not sufficient evidence to…
The boiling point of 16 samples of a certain brand of hydrogenated vegetable oil used in a fryer was collected, resulting in Xbar=152.1 degrees. Assume that the distribution of melting point is normal with o=3.20. If the boiling point is different than 150 degrees, then either the oil will be too hot and will burn food or it will be too cool and will not properly cook the food. Is the sample mean significantly different from the target of 150 degrees? Use alpha=0.01 Но: H1: Define critical (rejection) region(s): Calculate the appropriate test statistic: What decision do we make? What this decision means in terms of this problem?
The table below lists measured amounts of redshift and the distances (billions of light-years) to randomly selected astronomical objects. Find the (a) explained variation, (b) unexplained variation, and (c) indicated prediction interval. There is sufficient evidence to support a claim of a linear correlation, so it is reasonable to use the regression equation when making predictions. For the prediction interval, use a 90% confidence level with a redshift of 0.0126. Redshift Distance 0.0238 0.31 a. Find the explained variation. 0.0543 0.74 (Round to six decimal places as needed.) b. Find the unexplained variation. (Round to six decimal places as needed.) c. Find the indicated prediction interval. 0.0722 1.02 billion light-years
2. Suppose the chamber of commerce at Pyramid Lake advertises that the average length of trout caught at the lake is μ = 19 inches. However, a fishing magazine survey reported that for a random sample of 51 fish caught, the mean length was x = 18.5 inches with estimated standard deviation s = 3.2 inches. Do these data indicate that the average length of the trout caught at Pyramid Lake is less than μ = 10 inches? (Use α = 0.05)
The average height X and weight Y of males in population have a bivariate normal distribution with means µX 1.80 m., µy 90.0 kgs and standard deviations Ox = 0.30 m., oy = 15.3 kgs respectively. The correlation coefficient between X and Y is p= 0.80.
Total fat content (including saturated fat and trans fats) is a key characteristic of cheese. Assume that for a given type of cheese, total fat content (10-1 g/g of cheese) follows a normal distribution with a population mean of 2.85 (unit) and a population variance of 0.01 (unit2). Such an assumption is reasonable because fat content varies inside cheese and the “errors” around the mean total fat content (i.e. the value appearing on the etiquette) are distributed like a bell shape. a) What is the probability that the total fat content of this cheese exceeds 3 (unit)? b) What is the probability that the total fat content varies from 2.8 to 3 (unit)?

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