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Brase & Brase-Understandable Stats Internat'l 10/e (Homework)

James Finch

Statistics, section 2, Fall 2019

Instructor: Dr. Friendly

Current Score : 19 / 23

Due : Sunday, January 27, 2030 23:30 EST

Last Saved : n/a Saving...  ()

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19/23 (82.6%)

  • Instructions

    Create your course assignments by selecting questions from our bank of end-of-section exercises.

    While doing their homework, students can link to the relevant section from the book using the Read It links.

    In this assignment we present several textbook question types found in Understandable Statistics: Concepts and Methods, International Version 10/e by Charles Henry Brase and Corinne Pellillo Brase, published by Brooks/Cole. This demo assignment allows many submissions and allows you to try another version of the same question for practice wherever the problem has randomized values.

Assignment Submission

For this assignment, you submit answers by question parts. The number of submissions remaining for each question part only changes if you submit or change the answer.

Assignment Scoring

Your last submission is used for your score.

1. –/3 points BBUnderStatINT10 5.1.007. My Notes
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We can use the random number table to simulate outcomes from a given discrete probability distribution. Jose plays basketball and has probability 0.7 of making a free-throw shot. Let x be the random variable that counts the number of successful shots out of 10 attempts. Consider the digits 0 through 9 of the random number table. Since Jose has a 70% chance of making a shot, assign the digits 0 through 6 to "making a basket from the free throw line" and the digits 7 through 9 to "missing the shot."
(a) Do 70% of the possible digits 0 through 9 represent "making a basket"?
    


(b) Start at line 2, column 1 of the random number table. Going across the row, determine the results of 10 "trials." How many free-throw shots are successful in this simulation?

(c) Your friend decides to assign the digits 0 through 2 to "missing the shot" and the digits 3 through 9 to "making the basket." Is this assignment valid? Explain.
    
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2. –/1 points BBUnderStatINT10 5.2.001. My Notes
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For a binomial experiment, how many outcomes are possible for each trial? What are the possible outcomes?
    
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3. –/6 points BBUnderStatINT10 5.3.008. My Notes
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The figures below show histograms of several binomial distributions with n = 6 trials. Match the given probability of success with the best graph.
(a) p = 0.30 goes with graph .

(b) p = 0.50 goes with graph .

(c) p = 0.65 goes with graph .

(d) p = 0.90 goes with graph .

(e) In general, when the probability of success p is close to 0.5, would you say that the graph is more symmetrical or more skewed?
    


In general, when the probability of success p is close to 1, would you say that the graph is skewed to the right or to the left? What about when p is close to 0?
    

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4. –/3 points BBUnderStatINT10 5.3.012.S. My Notes
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The Denver Post reported that a recent Audit of Los Angeles 911 calls showed that 85% were not emergencies. Suppose the 911 operators in Los Angeles have just received three calls.
A button hyperlink to the SALT program that reads: Use SALT.
(a) What is the probability that all three calls are, in fact, emergencies? (Round your answer to three decimal places.)


(b) What is the probability that two or more calls are not emergencies? (Round your answer to three decimal places.)


(c) What is the smallest number of calls n that the 911 operators need to answer to be at least 96% (or more) sure that at least one call is, in fact, an emergency? (Enter your answer as a whole number.)
calls
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5. –/5 points BBUnderStatINT10 5.4.009. My Notes
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Susan is taking Western Civilization this semester on a pass/fail basis. The department teaching the course has a history of passing 80% of the students in Western Civilization each term. Let n = 1, 2, 3, ... represent the number of times a student takes Western Civilization until the first passing grade is received. (Assume the trials are independent.)
(a) Write out a formula for the probability distribution of the random variable n. (Use p and n in your answer.)
P(n) =


(b) What is the probability that Susan passes on the first try (n = 1)? (Use 2 decimal places.)


(c) What is the probability that Susan first passes on the second try (n = 2)? (Use 3 decimal places.)


(d) What is the probability that Susan needs three or more tries to pass Western Civilization? (Use 3 decimal places.)


(e) What is the expected number of attempts at Western Civilization Susan must make to have her (first) pass? Hint: Use μ for the geometric distribution and round.
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6. –/5 points BBUnderStatINT10 5.4.016. My Notes
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The Denver Post reported that, on average, a large shopping center had an incident of shoplifting caught by security 2.3 times every five hours. The shopping center is open from 10 A.M. to 9 P.M. (11 hours). Let r be the number of shoplifting incidents caught by security in an 11-hour period during which the center is open.
(a) Explain why the Poisson probability distribution would be a good choice for the random variable r.
    


What is λ? (Use 2 decimal places.)


(b) What is the probability that from 10 A.M. to 9 P.M. there will be at least one shoplifting incident caught by security? (Use 4 decimal places.)


(c) What is the probability that from 10 A.M. to 9 P.M. there will be at least three shoplifting incidents caught by security? (Use 4 decimal places.)


(d) What is the probability that from 10 A.M. to 9 P.M. there will be no shoplifting incidents caught by security? (Use 4 decimal places.)
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