Essentials of Statistics for the Behavioral Sciences
8th Edition
ISBN: 9781133956570
Author: Frederick J Gravetter, Larry B. Wallnau
Publisher: Cengage Learning
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Chapter 6, Problem 20P
A report in 2010 indicates that Americans between the ages of 8 and 18 spend an average of μ = 7.5 hours per day using some sort of electronic device such as smart phones, computers, or tablets. Assume that the distribution of times is normal with a standard deviation of σ = 2.5 hours and find the following values.
- a. What is the
probability of selecting an individual who uses electronic devices more than 12 hours a day? - b. What proportion of 8- to 18-year-old Americans spend between 5 and 10 hours per day using electronic devices? In symbols. p(5 < X < 10) = ?
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30. An individual who has automobile insurance from a certain company is randomly selected. Let Y be the num- ber of moving violations for which the individual was cited during the last 3 years. The pmf of Y isy | 1 2 4 8 16p(y) | .05 .10 .35 .40 .10
a.Compute E(Y).b. Suppose an individual with Y violations incurs a surcharge of $100Y^2. Calculate the expected amount of the surcharge.
24. An insurance company offers its policyholders a num- ber of different premium payment options. For a ran- domly selected policyholder, let X = the number of months between successive payments. The cdf of X is as follows:
F(x)=0.00 : x < 10.30 : 1≤x<30.40 : 3≤ x < 40.45 : 4≤ x <60.60 : 6≤ x < 121.00 : 12≤ x
a. What is the pmf of X?b. Using just the cdf, compute P(3≤ X ≤6) and P(4≤ X).
Chapter 6 Solutions
Essentials of Statistics for the Behavioral Sciences
Ch. 6.1 - A survey of the students in a psychology class...Ch. 6.1 - A jar contains 10 red marbles and 30 blue marbles....Ch. 6.1 - Suppose that you are going to select a random...Ch. 6.2 - Find the proportion of a normal distribution that...Ch. 6.2 - For a normal distribution, find the z-score...Ch. 6.2 - Prob. 3LCCh. 6.3 - For a normal distribution with a mean of = 60 and...Ch. 6.3 - Scores on the Mathematics section of the SAT...Ch. 6.3 - What is the probability of selecting a score...Ch. 6 - A local hardware store has a Savings Wheel at the...
Ch. 6 - A psychology class consists of 14 males and 36...Ch. 6 - What are the two requirements for a random sample?Ch. 6 - Draw a vertical line through a normal distribution...Ch. 6 - Draw a vertical line through a normal distribution...Ch. 6 - Find each of the following probabilities for a...Ch. 6 - What proportion of a normal distribution is...Ch. 6 - Find each of the following probabilities for a...Ch. 6 - Find the z-score location of a vertical line that...Ch. 6 - Find the z-score boundaries that separate a normal...Ch. 6 - A normal distribution has a mean of = 70 and a...Ch. 6 - A normal distribution has a mean of = 30 and a...Ch. 6 - For a normal distribution with a mean of = 60 and...Ch. 6 - IQ test scores are standardized to produce a...Ch. 6 - The distribution of SAT scores in normal with =...Ch. 6 - According to a recent, people smile an average of ...Ch. 6 - A recent newspaper article reported the results of...Ch. 6 - Information from the Department of Motor Vehicles...Ch. 6 - A consumer survey indicates that the average...Ch. 6 - A report in 2010 indicates that Americans between...Ch. 6 - Rochester. New York, averages = 21.9 inches of...
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