Probability and Statistics for Engineering and the Sciences

9th Edition

ISBN: 9781305251809

Author: Jay L. Devore

Publisher: Cengage Learning

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2-Proportion Test

In a 2-proportion test, two separate proportions are measured at the same time, and their similarity is evaluated. It is also known as a 2-proportion z-test, and a comparison of two different proportions is done in this method.

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Chapter 5.4, Problem 48E

The National Health Statistics Reports dated Oct. 22, 2008, stated that for a sample size of 277 18-year-old American males, the sample mean waist circumference was 86.3 cm. A somewhat complicated method was used to estimate various population percentiles, resulting in the following values:

5^th	10^th	25^th	50^th	75^th	90^th	95^th
69.6	70.9	75.2	81.3	95.4	107.1	116.4

a. Is it plausible that the waist size distribution is at least approximately normal? Explain your reasoning. If your answer is no, conjecture the shape of the population distribution.
1. b. Suppose that the population mean waist size is 85 cm and that the population standard deviation is 15 cm. How likely is it that a random sample of 277 individuals will result in a sample mean waist size of at least 86.3 cm?
2. c. Referring back to (b), suppose now that the population mean waist size in 82 cm. Now what is the (approximate) probability that the sample mean will be at least 86.3 cm? In light of this calculation, do you think that 82 cm is a reasonable value for μ?

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.

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Chapter 5 Solutions

Probability and Statistics for Engineering and the Sciences

Ch. 5.1 - Prob. 1E Ch. 5.1 - A large but sparsely populated county has two...Ch. 5.1 - A certain market has both an express checkout line...Ch. 5.1 - Return to the situation described in Exercise 3....Ch. 5.1 - The number of customers waiting for gift-wrap...Ch. 5.1 - Let X denote the number of Canon SLR cameras sold...Ch. 5.1 - Prob. 7E Ch. 5.1 - A stockroom currently has 30 components of a...Ch. 5.1 - Each front tire on a particular type of vehicle is...Ch. 5.1 - Prob. 10E

Ch. 5.1 - Two different professors have just submitted final...Ch. 5.1 - Two components of a minicomputer have the...Ch. 5.1 - Prob. 13E Ch. 5.1 - Suppose that you have ten lightbulbs, that the...Ch. 5.1 - Prob. 15E Ch. 5.1 - Prob. 16E Ch. 5.1 - An ecologist wishes to select a point inside a...Ch. 5.1 - Refer to Exercise 1 and answer the following...Ch. 5.1 - The joint pdf of pressures for right and left...Ch. 5.1 - Let X1, X2, X3, X4, X5, and X6 denote the numbers...Ch. 5.1 - Let X1, X2, and X3 be the lifetimes of components...Ch. 5.2 - An instructor has given a short quiz consisting of...Ch. 5.2 - The difference between the number of customers in...Ch. 5.2 - Six individuals, including A and B, take seats...Ch. 5.2 - A surveyor wishes to lay out a square region with...Ch. 5.2 - Prob. 26E Ch. 5.2 - Annie and Alvie have agreed to meet for lunch...Ch. 5.2 - Show that if X and Y are independent rvs, then...Ch. 5.2 - Compute the correlation coefficient for X and Y...Ch. 5.2 - Prob. 30E Ch. 5.2 - a. Compute the covariance between X and Y in...Ch. 5.2 - Reconsider the minicomputer component lifetimes X...Ch. 5.2 - Prob. 33E Ch. 5.2 - a. Recalling the definition of 2 for a single rv...Ch. 5.2 - a. Use the rules of expected value to show that...Ch. 5.2 - Show that if Y = aX + b (a 0), then Corr(X, Y)...Ch. 5.3 - A particular brand of dishwasher soap is sold in...Ch. 5.3 - There are two traffic lights on a commuters route...Ch. 5.3 - It is known that 80% of all brand A external hard...Ch. 5.3 - A box contains ten sealed envelopes numbered 1, ....Ch. 5.3 - Let X be the number of packages being mailed by a...Ch. 5.3 - A company maintains three offices in a certain...Ch. 5.3 - Suppose the amount of liquid dispensed by a...Ch. 5.4 - Youngs modulus is a quantitative measure of...Ch. 5.4 - Refer to Exercise 46. Suppose the distribution is...Ch. 5.4 - The National Health Statistics Reports dated Oct....Ch. 5.4 - There are 40 students in an elementary statistics...Ch. 5.4 - Let X denote the courtship time for a randomly...Ch. 5.4 - The time taken by a randomly selected applicant...Ch. 5.4 - The lifetime of a certain type of battery is...Ch. 5.4 - Rockwell hardness of pins of a certain type is...Ch. 5.4 - Suppose the sediment density (g/cm) of a randomly...Ch. 5.4 - The number of parking tickets issued in a certain...Ch. 5.4 - A binary communication channel transmits a...Ch. 5.4 - Suppose the distribution of the time X (in hours)...Ch. 5.5 - A shipping company handles containers in three...Ch. 5.5 - Let X1, X2, and X3 represent the times necessary...Ch. 5.5 - Refer back to Example 5.31. Two cars with...Ch. 5.5 - Exercise 26 introduced random variables X and Y,...Ch. 5.5 - Manufacture of a certain component requires three...Ch. 5.5 - Refer to Exercise 3. a. Calculate the covariance...Ch. 5.5 - Suppose your waiting time for a bus in the morning...Ch. 5.5 - Suppose that when the pH of a certain chemical...Ch. 5.5 - If two loads are applied to a cantilever beam as...Ch. 5.5 - One piece of PVC pipe is to be inserted inside...Ch. 5.5 - Two airplanes are flying in the same direction in...Ch. 5.5 - Three different roads feed into a particular...Ch. 5.5 - Consider a random sample of size n from a...Ch. 5.5 - In Exercise 66, the weight of the beam itself...Ch. 5.5 - I have three errands to take care of in the...Ch. 5.5 - Suppose the expected tensile strength of type-A...Ch. 5.5 - In an area having sandy soil, 50 small trees of a...Ch. 5 - A restaurant serves three fixed-price dinners...Ch. 5 - In cost estimation, the total cost of a project is...Ch. 5 - Prob. 77SE Ch. 5 - According to the article Reliability Evaluation of...Ch. 5 - Suppose that for a certain individual, calorie...Ch. 5 - The mean weight of luggage checked by a randomly...Ch. 5 - We have seen that if E(X1) = E(X2) = =E(Xn) = ,...Ch. 5 - Suppose the proportion of rural voters in a...Ch. 5 - Let denote the true pH of a chemical compound. A...Ch. 5 - If the amount of soft drink that I consume on any...Ch. 5 - Refer to Exercise 58, and suppose that the Xis are...Ch. 5 - A student has a class that is supposed to end at...Ch. 5 - Garbage trucks entering a particular...Ch. 5 - Each customer making a particular Internet...Ch. 5 - a. Use the general formula for the variance of a...Ch. 5 - Suppose a randomly chosen individuals verbal score...Ch. 5 - Prob. 91SE Ch. 5 - Prob. 92SE Ch. 5 - Prob. 93SE Ch. 5 - Let A denote the percentage of one constituent in...Ch. 5 - Let X1, . . . , Xn be independent rvs with mean...Ch. 5 - A more accurate approximation to E[h(X1, . . . ,...Ch. 5 - Prob. 97SE Ch. 5 - Prob. 98SE

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