Probability and Statistics for Engineering and the Sciences
9th Edition
ISBN: 9781305251809
Author: Jay L. Devore
Publisher: Cengage Learning
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Chapter 4.4, Problem 63E
A consumer is trying to decide between two long-distance calling plans. The first one charges a flat rate of10¢ per minute, whereas the second charges a flat rate of 99¢ for calls up to 20 minutes in duration and then 10¢ for each additional minute exceeding 20 (assume that calls lasting a noninteger number of minutes are charged proportionately to a whole-minute’s charge). Suppose the consumer’s distribution of call duration is exponential with parameter λ
a. Explain intuitively how the choice of calling plan should depend on what the expected call duration is.
b. Which plan is better if expected call duration is10 minutes? 15 minutes? [Hint: Let h1(x) denote the cost for the first plan when call duration is x minutes and let h2(x) be the cost function for the second plan. Give expressions for these two cost
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Chapter 4 Solutions
Probability and Statistics for Engineering and the Sciences
Ch. 4.1 - The current in a certain circuit as measured by an...Ch. 4.1 - Suppose the reaction temperature X (in C) in a...Ch. 4.1 - The error involved in making a certain measurement...Ch. 4.1 - Let X denote the vibratory stress (psi) on a wind...Ch. 4.1 - A college professor never finishes his lecture...Ch. 4.1 - The actual tracking weight of a stereo cartridge...Ch. 4.1 - The article Second Moment Reliability Evaluation...Ch. 4.1 - Prob. 8ECh. 4.1 - Based on an analysis of sample data, the article...Ch. 4.1 - A family of pdfs that has been used to approximate...
Ch. 4.2 - Let X denote the amount of time a book on two-hour...Ch. 4.2 - The cdf for X (= measurement error) of Exercise 3...Ch. 4.2 - Prob. 13ECh. 4.2 - The article Modeling Sediment and Water Column...Ch. 4.2 - Let X denote the amount of space occupied by an...Ch. 4.2 - The article A Model of Pedestrians Waiting Times...Ch. 4.2 - Let X have a uniform distribution on the interval...Ch. 4.2 - Let X denote the voltage at the output of a...Ch. 4.2 - Let X be a continuous rv with cdf...Ch. 4.2 - Consider the pdf for total waiting time Y for two...Ch. 4.2 - An ecologist wishes to mark off a circular...Ch. 4.2 - The weekly demand for propane gas (in 1000s of...Ch. 4.2 - If the temperature at which a certain compound...Ch. 4.2 - Let X have the Pareto pdf f(x;k,)={kkxk+1x0x...Ch. 4.2 - Let X be the temperature in C at which a certain...Ch. 4.2 - Let X be the total medical expenses (in 1000s of...Ch. 4.2 - Prob. 27ECh. 4.3 - Let Z be a standard normal random variable and...Ch. 4.3 - In each case, determine the value of the constant...Ch. 4.3 - Find the following percentiles for the standard...Ch. 4.3 - Determine z for the following values of : a. =...Ch. 4.3 - Suppose the force acting on a column that helps to...Ch. 4.3 - Mopeds (small motorcycles with an engine capacity...Ch. 4.3 - The article Reliability of Domestic-Waste Biofilm...Ch. 4.3 - In a road-paving process, asphalt mix is delivered...Ch. 4.3 - Spray drift is a constant concern for pesticide...Ch. 4.3 - Suppose that blood chloride concentration (mmol/L)...Ch. 4.3 - There are two machines available for cutting corks...Ch. 4.3 - The defect length of a corrosion defect in a...Ch. 4.3 - The article Monte Carlo SimulationTool for Better...Ch. 4.3 - The automatic opening device of a military cargo...Ch. 4.3 - The temperature reading from a thermocouple placed...Ch. 4.3 - Vehicle speed on a particular bridge in China can...Ch. 4.3 - If bolt thread length is normally distributed,...Ch. 4.3 - A machine that produces ball bearings has...Ch. 4.3 - The Rockwell hardness of a metal is determined by...Ch. 4.3 - The weight distribution of parcels sent in a...Ch. 4.3 - Suppose Appendix Table A.3 contained (z) only for...Ch. 4.3 - Consider babies born in the normal range of 3743...Ch. 4.3 - In response to concerns about nutritional contents...Ch. 4.3 - Chebyshevs inequality, (see Exercise 44, Chapter...Ch. 4.3 - Let X denote the number of flaws along a 100-m...Ch. 4.3 - Let X have a binomial distribution with parameters...Ch. 4.3 - Suppose that 10% of all steel shafts produced by a...Ch. 4.3 - Suppose only 75% of all drivers in a certain state...Ch. 4.3 - Show that the relationship between a general...Ch. 4.3 - a. Show that if X has a normal distribution with...Ch. 4.3 - There is no nice formula for the standard normal...Ch. 4.4 - Let X = the time between two successive arrivals...Ch. 4.4 - Let X denote the distance (m) that an animal moves...Ch. 4.4 - Data collected at Toronto Pearson International...Ch. 4.4 - The article Microwave Observations of Daily...Ch. 4.4 - A consumer is trying to decide between two...Ch. 4.4 - Evaluate the following: a. (6) b. (5/2) c. F(4; 5)...Ch. 4.4 - Let X denote the data transfer time (ms) in a grid...Ch. 4.4 - The two-parameter gamma distribution can be...Ch. 4.4 - Suppose that when a transistor of a certain type...Ch. 4.4 - The special case of the gamma distribution in...Ch. 4.4 - A system consists of five identical components...Ch. 4.4 - If X has an exponential distribution with...Ch. 4.4 - a. The event {X2 y} is equivalent to what event...Ch. 4.5 - The lifetime X (in hundreds of hours) of a certain...Ch. 4.5 - The authors of the article A Probabilistic...Ch. 4.5 - Prob. 74ECh. 4.5 - Let X have a Weibull distribution with the pdf...Ch. 4.5 - The article The Statistics of Phytotoxic Air...Ch. 4.5 - Prob. 77ECh. 4.5 - The article On Assessing the Accuracy of Offshore...Ch. 4.5 - Nonpoint source loads are chemical masses that...Ch. 4.5 - a. Use Equation (4.13) to write a formula for the...Ch. 4.5 - Sales delay is the elapsed time between the...Ch. 4.5 - As in the case of the Weibull and Gamma...Ch. 4.5 - What condition on and is necessary for the...Ch. 4.5 - Suppose the proportion X of surface area in a...Ch. 4.5 - Let X have a standard beta density with parameters...Ch. 4.5 - Stress is applied to a 20-in. steel bar that is...Ch. 4.6 - The accompanying normal probability plot was...Ch. 4.6 - A sample of 15 female collegiate golfers was...Ch. 4.6 - Prob. 89ECh. 4.6 - The article A Probabilistic Model of Fracture in...Ch. 4.6 - Construct a normal probability plot for the...Ch. 4.6 - The article The Load-Life Relationship for M50...Ch. 4.6 - Prob. 93ECh. 4.6 - The accompanying observations are precipitation...Ch. 4.6 - Use a statistical software package to construct a...Ch. 4.6 - Prob. 96ECh. 4.6 - The following failure time observations (1000s of...Ch. 4 - Let X = the time it takes a read/write head to...Ch. 4 - Prob. 99SECh. 4 - Let X denote the time to failure (in years) of a...Ch. 4 - The completion time X for a certain task has cdf...Ch. 4 - Let X represent the number of individuals who...Ch. 4 - The article Computer Assisted Net Weight...Ch. 4 - When circuit boards used in the manufacture of...Ch. 4 - Prob. 105SECh. 4 - The reaction time (in seconds) to a certain...Ch. 4 - Let X denote the temperature at which a certain...Ch. 4 - An oocyte is a female germ cell involved in...Ch. 4 - Prob. 109SECh. 4 - Prob. 110SECh. 4 - Prob. 111SECh. 4 - The article Error Distribution in Navigation (J....Ch. 4 - Prob. 113SECh. 4 - Suppose a particular state allows individuals...Ch. 4 - Let Ii be the input current to a transistor and I0...Ch. 4 - Prob. 116SECh. 4 - Prob. 117SECh. 4 - a. Suppose the lifetime X of a component, when...Ch. 4 - Prob. 119SECh. 4 - Prob. 120SECh. 4 - The article Three Sisters Give Birth on the Same...Ch. 4 - Let X denote the lifetime of a component, with f...Ch. 4 - Prob. 123SECh. 4 - Prob. 124SECh. 4 - A function g(x) is convex if the chord connecting...Ch. 4 - Let X have a Weibull distribution with parameters ...Ch. 4 - An individuals credit score is a number calculated...Ch. 4 - Prob. 128SE
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