A First Course in Probability
9th Edition
ISBN: 9780321794772
Author: Sheldon Ross
Publisher: PEARSON
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Chapter 2, Problem 2.46P
How many people have to be in a room in order that the
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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…
8.1.1 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?
8.1.8 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?
Chapter 2 Solutions
A First Course in Probability
Ch. 2 - A box contains 3 marbles: 1 red, 1 green, and 1...Ch. 2 - In an experiment, die is rolled continually until...Ch. 2 - Two dice are thrown. Let E be the event that the...Ch. 2 - A, B, and C take turns flipping a coin. The first...Ch. 2 - A system is composed of 5 components, each of...Ch. 2 - A hospital administrator codes incoming patients...Ch. 2 - Consider an experiment that consists of...Ch. 2 - Suppose that A and B are mutually exclusive events...Ch. 2 - A retail establishment accepts either the American...Ch. 2 - Sixty percent of the students at a certain school...
Ch. 2 - A total of 28 percent of American males smoke...Ch. 2 - An elementary school is offering 3 language...Ch. 2 - A certain town with a population of 100.000 has 3...Ch. 2 - The following data were given in a study of a...Ch. 2 - If it is assumed that all (525) poker hands are...Ch. 2 - Poker dice is played by simultaneously rolling 5...Ch. 2 - Twenty five people, consisting of 15 women and 10...Ch. 2 - Two cards are randomly selected from an ordinary...Ch. 2 - Two symmetric dice have had two of their sides...Ch. 2 - Suppose that you are playing blackjack against a...Ch. 2 - A small community organization consists of 20...Ch. 2 - Consider the following technique for shuffling a...Ch. 2 - A pair of fair dice is rolled. What is the...Ch. 2 - It two dice are rolled, what is the probability...Ch. 2 - A pair of dice is rolled until a sum of either 5...Ch. 2 - The game of craps is played as follows: A player...Ch. 2 - An urn contains 3 red and 7 black balls. Players A...Ch. 2 - An urn contains 5 red, 6 blue, and 8 green balls....Ch. 2 - An urn contains n white and m black balls, where n...Ch. 2 - The chess clubs of two schools consist of,...Ch. 2 - A 3-person basketball team consists of a guard, a...Ch. 2 - A group of individuals containing b boys and g...Ch. 2 - A forest contains 20 elk, of which 5 are captured,...Ch. 2 - The second Earl of Yarborough is reported to have...Ch. 2 - Seven balls are randomly withdrawn from an urn...Ch. 2 - Two cards are chosen at random from a deck of 52...Ch. 2 - An instructor gives her class a set of 10 problems...Ch. 2 - There are n socks. 3 of which are red, in a...Ch. 2 - There are 5 hotels in a certain town. If 3 people...Ch. 2 - A town contains 4 people who repair televisions....Ch. 2 - If a die is rolled 4 times, what is the...Ch. 2 - Two dice are thrown n times in succession. Compute...Ch. 2 - a. If N people, including A and B, are randomly...Ch. 2 - Five people, designated as A, B, C, D, E, are...Ch. 2 - A woman has n keys, of which one will open her...Ch. 2 - How many people have to be in a room in order that...Ch. 2 - Suppose that 5 of the numbers 1, 2,..., 14 are...Ch. 2 - Given 20 people, what is the probability that...Ch. 2 - A group of 6 men and 6 women is randomly divided...Ch. 2 - In a hand of bridge, find the probability that you...Ch. 2 - Suppose that n balls are randomly distributed into...Ch. 2 - A closet contains 10 pairs of shoes. If 8 shoes...Ch. 2 - If 4 married couples are arranged in a row, find...Ch. 2 - Compute the probability that a bridge hand is void...Ch. 2 - Compute the probability that a hand of 13 cards...Ch. 2 - Two players play the following game: Player A...Ch. 2 - Prove the following relations: EFEEFCh. 2 - Prove the following relations: If EF, then FCEC.Ch. 2 - Prove the following relations: 3. F=FEFEC and...Ch. 2 - Prove the following relations: (1Ei)F=1EiF and...Ch. 2 - For any sequence of events E1,E2,..., define a new...Ch. 2 - Let E, F, and C be three events. Find expressions...Ch. 2 - Use Venn diagrams a. to simplify the expression...Ch. 2 - Prob. 2.8TECh. 2 - Suppose that an experiment is performed n times...Ch. 2 - Prove...Ch. 2 - If P(E)=.9 and P(F)=.8, show that P(EF).7. In...Ch. 2 - Show that the probability that exactly one of the...Ch. 2 - Prove that P(EF)=P(E)P(EF).Ch. 2 - Prove Proposition 4.4 by mathematical induction.Ch. 2 - An urn contains M white and N black balls. If a...Ch. 2 - Use induction to generalize Bonferronis inequality...Ch. 2 - Consider the matching problem. Example 5m, and...Ch. 2 - Let fn, denote the number of ways of tossing a...Ch. 2 - An urn contains n red and m blue balls. They are...Ch. 2 - Consider an experiment whose sample space consists...Ch. 2 - Consider Example 50, which is concerned with the...Ch. 2 - A cafeteria offers a three-course meal consisting...Ch. 2 - A customer visiting the suit department of a...Ch. 2 - A deck of cards is dealt out. What is the...Ch. 2 - Let A denote the event that the midtown...Ch. 2 - An ordinary deck of 52 cards is shuffled. What is...Ch. 2 - Urn A contains 3 red and 3 black balls, whereas...Ch. 2 - In a state lottery, a player must choose 8 of the...Ch. 2 - From a group of 3 first-year students, 4...Ch. 2 - For a finite set A, let N(A) denote the number of...Ch. 2 - Consider an experiment that consists of 6 horses,...Ch. 2 - A 5-card hand is dealt from a well-shuffled deck...Ch. 2 - A basketball team consists of 6 frontcourt and 4...Ch. 2 - Suppose that a person chooses a letter at random...Ch. 2 - Prove Booles inequality P(i=1Ai)i=1P(Ai)Ch. 2 - Show that if P(Ai)=1 for all i1, then P(i=1Ai)=1.Ch. 2 - Let Tk(n) denote the number of partitions of the...Ch. 2 - Five balls are randomly chosen, without...Ch. 2 - Four red, 8 blue, and 5 green balls are randomly...Ch. 2 - Ten cards are randomly chosen from a deck of 52...Ch. 2 - Balls are randomly removed from an urn initially...
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- 8.1.12 Ishikawa et al. [“Evaluation of Adhesiveness of Acinetobacter sp. Tol 5 to Abiotic Surfaces,” Journal of Bioscience and Bioengineering (Vol. 113(6), pp. 719–725)] studied the adhesion of various biofilms to solid surfaces for possible use in environmental technologies. Adhesion assay is conducted by measuring absorbance at A590. Suppose that for the bacterial strain Acinetobacter, five measurements gave readings of 2.69, 5.76, 2.67, 1.62, and 4.12 dyne-cm2. Assume that the standard deviation is known to be 0.66 dyne-cm2. a. Find a 95% confidence interval for the mean adhesion. b. If the scientists want the confidence interval to be no wider than 0.55 dyne-cm2, how many observations should they take?arrow_forwardAnswer questions 8.2.1 and 8.2.2 respectivelyarrow_forward8.2.3 A research engineer for a tire manufacturer is investigating tire life for a new rubber compound and has built 16 tires and tested them to end-of-life in a road test. The sample mean and standard deviation are 60,139.7 and 3645.94 kilometers. Find a 95% confidence interval on mean tire life. 8.2.4 Determine the t-percentile that is required to construct each of the following one-sided confidence intervals: a. Confidence level = 95%, degrees of freedom = 14 b. Confidence level = 99%, degrees of freedom = 19 c. Confidence level = 99.9%, degrees of freedom = 24arrow_forward
- 8.1.6The yield of a chemical process is being studied. From previous experience, yield is known to be normally distributed and σ = 3. The past 5 days of plant operation have resulted in the following percent yields: 91.6, 88.75, 90.8, 89.95, and 91.3. Find a 95% two-sided confidence interval on the true mean yield. 8.1.7 .A manufacturer produces piston rings for an automobile engine. It is known that ring diameter is normally distributed with σ = 0.001 millimeters. A random sample of 15 rings has a mean diameter of x = 74.036 millimeters. a. Construct a 99% two-sided confidence interval on the mean piston ring diameter. b. Construct a 99% lower-confidence bound on the mean piston ring diameter. Compare the lower bound of this confi- dence interval with the one in part (a).arrow_forward8.1.2 .Consider the one-sided confidence interval expressions for a mean of a normal population. a. What value of zα would result in a 90% CI? b. What value of zα would result in a 95% CI? c. What value of zα would result in a 99% CI? 8.1.3 A random sample has been taken from a normal distribution and the following confidence intervals constructed using the same data: (38.02, 61.98) and (39.95, 60.05) a. What is the value of the sample mean? b. One of these intervals is a 95% CI and the other is a 90% CI. Which one is the 95% CI and why?arrow_forward8.1.4 . A confidence interval estimate is desired for the gain in a circuit on a semiconductor device. Assume that gain is normally distributed with standard deviation σ = 20. a. How large must n be if the length of the 95% CI is to be 40? b. How large must n be if the length of the 99% CI is to be 40? 8.1.5 Suppose that n = 100 random samples of water from a freshwater lake were taken and the calcium concentration (milligrams per liter) measured. A 95% CI on the mean calcium concentration is 0.49 g μ g 0.82. a. Would a 99% CI calculated from the same sample data be longer or shorter? b. Consider the following statement: There is a 95% chance that μ is between 0.49 and 0.82. Is this statement correct? Explain your answer. c. Consider the following statement: If n = 100 random samples of water from the lake were taken and the 95% CI on μ computed, and this process were repeated 1000 times, 950 of the CIs would contain the true value of μ. Is this statement correct? Explain your answerarrow_forward
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