Introduction to Probability and Statistics
14th Edition
ISBN: 9781133103752
Author: Mendenhall, William
Publisher: Cengage Learning
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Chapter 6, Problem 6.86SE
(a)
To determine
To find: The upper and lower
(b)
To determine
To find: Whether is it unusual to deliver a baby after 6 months.
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3. Bayesian Inference – Updating Beliefs
A medical test for a rare disease has the following characteristics:
Sensitivity (true positive rate): 99%
Specificity (true negative rate): 98%
The disease occurs in 0.5% of the population.
A patient receives a positive test result.
Questions:
a) Define the relevant events and use Bayes’ Theorem to compute the probability that the patient actually has the disease.b) Explain why the result might seem counterintuitive, despite the high sensitivity and specificity.c) Discuss how prior probabilities influence posterior beliefs in Bayesian inference.d) Suppose a second, independent test with the same accuracy is conducted and is also positive. Update the probability that the patient has the disease.
4. Linear Regression - Model Assumptions and Interpretation
A real estate analyst is studying how house prices (Y) are related to house size in square feet (X). A simple
linear regression model is proposed:
The analyst fits the model and obtains:
•
Ŷ50,000+150X
YBoB₁X + €
•
R² = 0.76
• Residuals show a fan-shaped pattern when plotted against fitted values.
Questions:
a) Interpret the slope coefficient in context.
b) Explain what the R² value tells us about the model's performance.
c) Based on the residual pattern, what regression assumption is likely violated? What might be the
consequence?
d) Suggest at least two remedies to improve the model, based on the residual analysis.
5. Probability Distributions – Continuous Random Variables
A factory machine produces metal rods whose lengths (in cm) follow a continuous uniform distribution on the interval [98, 102].
Questions:
a) Define the probability density function (PDF) of the rod length.b) Calculate the probability that a randomly selected rod is shorter than 99 cm.c) Determine the expected value and variance of rod lengths.d) If a sample of 25 rods is selected, what is the probability that their average length is between 99.5 cm and 100.5 cm? Justify your answer using the appropriate distribution.
Chapter 6 Solutions
Introduction to Probability and Statistics
Ch. 6.3 - Consider a standard normal random variable with =0...Ch. 6.3 - Find these probabilities associated with the...Ch. 6.3 - Calculate the area under the standard normal curve...Ch. 6.3 - Calculate the area under the standard normal curve...Ch. 6.3 - Find the following probabilities for the standard...Ch. 6.3 - Find these probabilities for the standard normal...Ch. 6.3 - a. Find a z0 such that P(zz0)=.025 . b. Find a z0...Ch. 6.3 - Prob. 6.8ECh. 6.3 - Prob. 6.9ECh. 6.3 - a. Find a z0 such that P(z0zz0)=.90 . b. Find a z0...
Ch. 6.3 - Find the following percentiles for the standard...Ch. 6.3 - A normal random variable x has mean =10 and...Ch. 6.3 - Prob. 6.13ECh. 6.3 - Prob. 6.14ECh. 6.3 - A normal random variable x has mean 35 and...Ch. 6.3 - Prob. 6.16ECh. 6.3 - A normal random variable x has an unknown mean and...Ch. 6.3 - Hamburger Meat The meat department at a local...Ch. 6.3 - Human Heights Human heights are one of many...Ch. 6.3 - Christmas Trees The diameters of Douglas firs...Ch. 6.3 - Cerebral Blood Flow Cerebral blood flow (CBF) in...Ch. 6.3 - Braking Distances For a car traveling 30 miles per...Ch. 6.3 - Elevator Capacities Suppose that you must...Ch. 6.3 - Sunflowers An experimenter publishing in the...Ch. 6.3 - Prob. 6.26ECh. 6.3 - Prob. 6.27ECh. 6.3 - Prob. 6.28ECh. 6.3 - Prob. 6.30ECh. 6.3 - How Many Words? A publisher has discovered that...Ch. 6.3 - Prob. 6.32ECh. 6.4 - Consider a binomial random variable x with n=25...Ch. 6.4 - Prob. 6.36ECh. 6.4 - Prob. 6.37ECh. 6.4 - Let x be a binomial random variable with n=15 and...Ch. 6.4 - Let x be a binomial random variable with n=100 and...Ch. 6.4 - Prob. 6.40ECh. 6.4 - Prob. 6.41ECh. 6.4 - Prob. 6.42ECh. 6.4 - Prob. 6.43ECh. 6.4 - Prob. 6.44ECh. 6.4 - Prob. 6.45ECh. 6.4 - Prob. 6.46ECh. 6.4 - No Shows Airlines and hotels often grant...Ch. 6.4 - Prob. 6.49ECh. 6.4 - Pepsi’s Market Share Two of the biggest soft drink...Ch. 6.4 - Prob. 6.52ECh. 6.4 - Prob. 6.53ECh. 6 - Prob. 6.54SECh. 6 - Prob. 6.55SECh. 6 - Prob. 6.56SECh. 6 - Prob. 6.57SECh. 6 - a. Find a z0 such that P(z0zz0)=.95 . b. Find a z0...Ch. 6 - Prob. 6.59SECh. 6 - Let x be a binomial random variable with n=36 and...Ch. 6 - Prob. 6.61SECh. 6 - Prob. 6.62SECh. 6 - Prob. 6.63SECh. 6 - Prob. 6.64SECh. 6 - Prob. 6.65SECh. 6 - Prob. 6.66SECh. 6 - Prob. 6.67SECh. 6 - Prob. 6.68SECh. 6 - Prob. 6.69SECh. 6 - Used Cars A used-car dealership has found that the...Ch. 6 - Washers The life span of a type of automatic...Ch. 6 - Prob. 6.74SECh. 6 - Prob. 6.75SECh. 6 - Prob. 6.77SECh. 6 - Prob. 6.78SECh. 6 - Prob. 6.79SECh. 6 - Prob. 6.80SECh. 6 - No Shows An airline finds that 5% of the persons...Ch. 6 - Prob. 6.82SECh. 6 - Plant Genetics In Exercise 5.75, a cross between...Ch. 6 - Prob. 6.84SECh. 6 - Prob. 6.86SECh. 6 - Prob. 6.87SECh. 6 - Introvert or Extrovert? A psychological...Ch. 6 - Normal Distribution? The chest measurements for...Ch. 6 - Prob. 6.91SECh. 6 - Prob. 6.92SECh. 6 - Prob. 6.93SECh. 6 - Prob. 6.94SECh. 6 - Prob. 6.95SECh. 6 - Prob. 6.96SECh. 6 - Prob. 6.97SE
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