A First Course in Probability
9th Edition
ISBN: 9780321794772
Author: Sheldon Ross
Publisher: PEARSON
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Textbook Question
Chapter 8, Problem 8.14STPE
Each new book donated to a library must be processed. Suppose that the time it takes to process a book has
a. approximate the
b. approximate the probability that at least 25 books will be processed in the first 240 minutes.
What assumptions have you made?
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Students have asked these similar questions
8.4.7 Use the data from Exercise 8.4.5 to compute the two-sided
Agresti-Coull CI on the proportion of digits read correctly.
Compare and discuss the relationship of this interval to the one
computed in Exercise 8.4.5.
8.6.5 Consider the fuel rod enrichment data described in Exercise 8.2.11. Compute a 90% prediction interval on the enrichment of the next rod tested. Compare the length of the prediction
interval with the length of the 99% CI on the population mean.
8.4.4 The Arizona Department of Transportation
wishes to survey state residents to determine what proportion of
the population would like to increase statewide highway speed
limits from 65 mph to 75 mph. How many residents does the
department need to survey if it wants to be at least 99% confident
that the sample proportion is within 0.05 of the true proportion?
8.4.5 The U.S. Postal Service (USPS) has used optical character
recognition (OCR) since the mid-1960s. In 1983, USPS began
deploying the technology to major post offices throughout the
country (www.britannica.com). Suppose that in a random sample
of 500 handwritten zip code digits, 466 were read correctly.
a. Construct a 95% confidence interval for the true proportion of correct digits that can be automatically read.
b. What sample size is needed to reduce the margin of error
to 1%?
c. How would the answer to part (b) change if you had
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correctly?
Chapter 8 Solutions
A First Course in Probability
Ch. 8 - Suppose that X is a random variable with mean and...Ch. 8 - From past experience, a professor knows that the...Ch. 8 - Use the central limit theorem to solve part (c) of...Ch. 8 - Let X1,...,X20 be independent Poisson random...Ch. 8 - Fifty numbers are rounded off to the nearest...Ch. 8 - A die is continually rolled until the total sum of...Ch. 8 - A person has 100 light bulbs whose lifetimes are...Ch. 8 - In Problem 8.7, suppose that it takes a random...Ch. 8 - If X is a gamma random variable with parameters...Ch. 8 - Civil engineers believe that W, the amount of...
Ch. 8 - Many people believe that the daily change of price...Ch. 8 - We have 100 components that we will put in use in...Ch. 8 - Student scores on exams given by a certain...Ch. 8 - A certain component is critical to the operation...Ch. 8 - An insurance company has 10.000 automobile...Ch. 8 - A.J. has 20 jobs that she must do in sequence,...Ch. 8 - Redo Example 5b under the assumption that the...Ch. 8 - Repeat part (a) of Problem 8.2 when it is known...Ch. 8 - A lake contains 4 distinct types of fish. Suppose...Ch. 8 - If X is a nonne9ative random variable with mean...Ch. 8 - Let X be a nonnegative random variable. Prove that...Ch. 8 - Prob. 8.22PCh. 8 - Let X be a Poisson random variable with mean 20....Ch. 8 - Prob. 8.24PCh. 8 - If X has variance 2, then , the positive square...Ch. 8 - If X has mean and standard deviation , the ratio...Ch. 8 - Compute the measurement signal-to-noise ratio-that...Ch. 8 - Let Zn,n1, be a sequence of random variables and...Ch. 8 - Prob. 8.5TECh. 8 - Prob. 8.6TECh. 8 - Prob. 8.7TECh. 8 - Explain why a gamma random variable with...Ch. 8 - Prob. 8.9TECh. 8 - If X is a Poisson random variable with mean , show...Ch. 8 - Prob. 8.11TECh. 8 - Prob. 8.12TECh. 8 - Prob. 8.13TECh. 8 - Prob. 8.14TECh. 8 - The number of automobiles sold weekly at a certain...Ch. 8 - Prob. 8.2STPECh. 8 - If E[X]=75E[Y]=75Var(X)=10var(Y)=12cov(X,Y)=3 give...Ch. 8 - Prob. 8.4STPECh. 8 - Prob. 8.5STPECh. 8 - Prob. 8.6STPECh. 8 - Prob. 8.7STPECh. 8 - Prob. 8.8STPECh. 8 - Prob. 8.9STPECh. 8 - A tobacco company claims that the amount of...Ch. 8 - Prob. 8.11STPECh. 8 - Prob. 8.12STPECh. 8 - The strong law of large numbers states that with...Ch. 8 - Each new book donated to a library must be...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, probability and related others by exploring similar questions and additional content below.Similar questions
- 8.6.4 Consider the test on the compressive strength of concrete described in Exercise 8.2.9. Compute a 90% prediction interval on the next specimen of concrete tested. 8.6.5 . SS Consider the fuel rod enrichment data described in Exercise 8.2.11. Compute a 90% prediction interval on the enrichment of the next rod tested. Compare the length of the prediction interval with the length of the 99% CI on the population mean.arrow_forwardAnswer questions 8S10 and 8S11 respectively.arrow_forward8.4.6 Information on a packet of seeds claims that 93% of them will germinate. Of the 200 seeds that were planted, only 180 germinated. a. Find a 95% confidence interval for the true proportion of seeds that germinate based on this sample. b. Does this seem to provide evidence that the claim is wrong? 8.6.1 Consider the tire-testing data described in Exercise 8.2.3. Compute a 95% prediction interval on the life of the next tire of this type tested under conditions that are similar to those employed in the original test. Compare the length of the prediction interval with the length of the 95% CI on the population mean.arrow_forward
- Answer questions 8.3.1 and 8.3.2 respectivelyarrow_forward8.2.7 The brightness of a television picture tube can be evaluated by measuring the amount of current required to achieve a particular brightness level. A sample of 10 tubes results in x = 317.2 and s = 15.7. Find (in microamps) a 99% confidence interval on mean current required. State any necessary assumptions about the underlying distribution of the data. 8.2.8 An article in the Journal of Composite Materials (December 1989, Vol. 23(12), pp. 1200–1215) describes the effect of delamination on the natural frequency of beams made from composite laminates. Five such delaminated beams were subjected to loads, and the resulting frequencies (in hertz) were as follows: 230.66, 233.05, 232.58, 229.48, 232.58 Check the assumption of normality in the population. Calculate a 90% two-sided confidence interval on mean natural frequency.arrow_forward8.2.5 An article in Obesity Research [“Impaired Pressure Natriuresis in Obese Youths” (2003, Vol. 11, pp. 745–751)] described a study in which all meals were provided for 14 lean boys for three days followed by one stress test (with a video-game task). The average systolic blood pressure (SBP) during the test was 118.3 mm HG with a standard deviation of 9.9 mm HG. Construct a 99% one-sided upper confidence interval for mean SBP. 8.2.6 An article in Medicine and Science in Sports and Exercise [“Maximal Leg-Strength Training Improves Cycling Economy in Previously Untrained Men” (2005, Vol. 37, pp. 131–136)] studied cycling performance before and after 8 weeks of leg-strength training. Seven previously untrained males performed leg-strength training 3 days per week for 8 weeks (with four sets of five replications at 85% of one repetition maximum). Peak power during incremental cycling increased to a mean of 315 watts with a standard deviation of 16 watts. Construct a 95% confidence…arrow_forward
- they take? 8.1.13 WP GO Tutorial An article in the Journal of Agricultural Science ["The Use of Residual Maximum Likelihood to Model Grain Quality Characteristics of Wheat with Variety, Climatic and Nitrogen Fertilizer Effects” (1997, Vol. 128, pp. 135–142)] investigated means of wheat grain crude protein content (CP) and Hagberg falling number (HFN) surveyed in the United Kingdom. The analysis used a variety of nitrogen fertilizer applications (kg N/ha), temperature (°C), and total monthly rainfall (mm). The following data below describe temperatures for wheat grown at Harper Adams Agricultural College between 1982 and 1993. The temperatures measured in June were obtained as follows: 15.2 14.2 14.0 12.2 14.4 12.5 14.3 14.2 13.5 11.8 15.2 Assume that the standard deviation is known to be σ = 0.5. a. Construct a 99% two-sided confidence interval on the mean temperature. b. Construct a 95% lower-confidence bound on the mean temperature. c. Suppose that you wanted to be 95% confident that…arrow_forward8.1.1 WP For a normal population with known variance σ², answer the following questions: - a. What is the confidence level for the interval x — 2.140/ √√n≤≤+2.140/√√n?arrow_forward8.1.8 A civil engineer is analyzing the compressives trength of concrete. Compressive strength is normally distributed with σ2 = 1000(psi)2. A random sample of 12 specimens has a mean compressive strength ofx = 3250 psi. a. Construct a 95% two-sided confidence interval on mean compressive strength. b. Construct a 99% two-sided confidence interval on mean compressive strength. Compare the width of this confidence interval with the width of the one found in part (a). 8.1.9Suppose that in Exercise 8.1.8 it is desired to estimate the compressive strength with an error that is less than 15 psi at 99% confidence. What sample size is required?arrow_forward
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