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Study Resources (Statistics)

  22.A marketing strategist would like to estimate the difference between the proportion of men who list “Action” as their favorite movie genre and the proportion of women who list “Action” as their favorite genre.  The strategist gathers a random sample of 300 men and 200 women.  Of the men, 156.
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  35.The density curve for a continuous random variable is shown below. Use this curve to find the following probabilities:   a) P(x < 1) b) P(2 < x < 3) c) P(x is at least 3)     You may use the following area formulas in your calculations:   Area of a rectangle: A = lw Area of a trapezoid: Area of a right triangle:           36.The.
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  SHORT ANSWER   10.Describe the difference between an estimation problem and a hypothesis testing problem.       11.Suppose a researcher is collecting data about the amount of soda Americans consume in one day.  If the researcher was to gather two separate representative samples from the population, differences may exist between these samples.  These differences may.
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  SHORT ANSWER   23.What is a random variable?     24.Using the notation C = continuous and D = discrete, indicate whether each of the random variables are discrete or continuous.   a) The number of defective lights in your school's main hallway     b) The barometric pressure at midnight     c) The number of staples left in a stapler     d) The number of sentences in.
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  29.Conventional home smoke alarms have too often failed to awaken sleeping children--they are remarkably resistant to being awakened by sound, even in the daytime! Researchers are studying the possibility that a personalized "voice" smoke alarm would be more effective than mere sound. The idea is that a recording of the.
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TRUE/FALSE   1.A random variable is discrete if the value of the random variable depends upon the outcome of a chance experiment.     2.A random variable is continuous if the set of possible values includes an entire interval on the number line.     3.The distribution of all values of a random variable is called a normal.
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  SHORT ANSWER   17.When comparing two population means, it is important to make the distinction between independent samples and paired samples. What makes two samples independent?     18.One method of human locomotion that appears to have no function except to express joy is skipping, a skill usually learned in early and middle childhood. In.
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  43.While playing Monopoly, Laura estimated the probabilities of the non-zero rents according to the following probability distribution:   x $10 $20 $50 $130 P(x) 0.20 0.20 0.40 0.20   Consider the random variable x = dollar amount in rent in a Monopoly roll.   a) If the table above specifies the probability distribution f(x), what is the mean of the random variable x?     b) If the probabilities are.
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  SHORT ANSWER   21.What is a sampling distribution of a statistic?         22.The principal at John F. Kennedy High School has been asked to provide the average number of classes taken by the students at KHS. Since the computer system is down, she takes her alphabetized list of students, randomly selects 50 students, determines.
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  SHORT ANSWER   23.Some limitations of the classical approach to probability were discussed in the text. Identify and briefly discuss one of these.         24.In a few sentences, distinguish between the classical and relative frequency approaches to probability.     25.At Beth & Mary's Ice Cream Emporium customers may choose to sprinkle toppings on their ice cream..
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  31.When the sample size is "large enough," the statistic p has an approximately normal sampling distribution. How does one determine if a sample size is large enough?       32.Determine the mean and standard deviation of the sampling distribution of when n = 100 and p = 0.65.       33.One method for estimating abundance.
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TRUE/FALSE   1.If the null hypothesis is not rejected, there is strong statistical evidence that the null hypothesis is true.     2.A type II error is made by failing to reject a false null hypothesis.     3.The level of significance of a test is the probability of making a type I error, given that the null.
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  26.One criticism of reading comprehension tests is that while they may measure reading comprehension, they also measure other factors not related to reading comprehension. A reading comprehension (RC) test on a major college entrance exam provides short English prose passages, and the examinees answer a set of multiple-choice items about.
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  61.In a study of the reaction times of left- and right-handers' reaction times to tones delivered to the right ear, the right-handers' scores were approximately normally distributed with a mean of 210 milliseconds and standard deviation of 40 milliseconds. The mean score for left-handers was 240 ms.   a) Sketch a normal distribution.
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TRUE/FALSE   1.Using an unbiased statistic guarantees that there will be no systematic tendency to under- or overestimate the value of the population characteristic and that estimates will almost always be relatively close to the true value.     2.A statistic that is unbiased with a small standard error is likely to result in an.
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  SHORT ANSWER   19.Explain in your own words what a hypothesis test is.       20.Explain in your own words the distinction between a null and alternative hypothesis.     21.One of the early decisions that must be made when performing a hypothesis test is the choice of significance level. Briefly describe the considerations that go into making.
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  52.Determine the following areas under the standard normal (z) curve.   a) The area under the z curve to the left of 2.53     b) The area under the z curve to the left of ?1.33     c) The area under the z curve to the right of 0.76     d) The area under the z curve to the right of ?1.47     e) The.
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  33.A small manufacturing firm has 250 employees. Fifty have been employed for less than 5 years and 125 have been with the company for over 10 years. Suppose that one employee is selected at random from a list of the employees. For the following events, compute the probabilities requested below.     A.
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  SHORT ANSWER   19.What is the difference between an unbiased statistic and a biased statistic?     20.When choosing a statistic for computing an estimate, what factors should be considered?       21.If the distribution of a population is symmetric, both the mean and median give unbiased estimates of the population mean. What criteria would you consider in.
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  MULTIPLE CHOICE   12.Which of the following symbols is used to indicate a population proportion?   a. b. c. d. e.       13.Which of the following statements is a population proportion?   a. A state census reports that 54% of the state’s citizens owns at least one dog.. b. Out of 50 randomly-selected individuals, 19 indicated that they snore during sleep. c. The mean lifetime of all.
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  MULTIPLE CHOICE   7.For which of the following sample sizes and values would it be appropriate to use to estimate a difference in population proportions?   I.    II.  III.   a. I only b. II only c. III only d. II and III only e. I, II, and III       8.A 90% confidence interval for is (–0.05, –0.002). Which of the following is the.
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TRUE/FALSE   1.Suppose researchers would like to determine the proportion of Americans who own dogs.  This would be a hypothesis testing problem.     2.When selecting an appropriate method for data analysis, one important consideration is the number of and type of variables involved in the situation.     3.When selecting an appropriate method for data analysis, the.
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  56.Let z denote a random variable having a standard normal distribution. Determine each of the following probabilities.   a) P(z < 1.28)     b) P(z < ?1.05)     c) P(z > ?2.51)     d) P(?1.30 < z < 1.54)           57.Let z denote a random variable having a standard normal distribution. Determine each of the following probabilities.   a) P(z < 1.36) b) P(z < ?2.05) c) P(z > ?1.15) d) P(?1.10 <.
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  28.As every Girl Scout knows, statistics teachers seriously love Girl Scout Cookies. The number of boxes of GS cookies statistics teachers order, like all important decisions made by statistics teachers, is determined by independent rolls of a 4-sided fair die. If a one appears, 6 boxes are ordered; if any.
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TRUE/FALSE   1.A statistic is a characteristic of the population.     2. and p are statistics.     3. and are statistics.     4.As n grows larger, the mean of the sampling distribution of gets closer to ?.     5.The standard deviation of the distribution of decreases as n increases.     6.The sampling distribution of tends to be more.
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  MULTIPLE CHOICE   9.Three different statistics are being considered for estimating a population characteristic. The sampling distributions of the three statistics are shown in the following illustration:   Which statistic would you recommend?   a. Statistic I b. Statistic II c. Statistic III d. Statistic I or  Statistic II e. Statistic II or Statistic III       10.A random sample will be selected from the population of all.
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  37.In a certain very large city, the Department of Transportation (D.O.T.) has organized a complex system of bus transportation. In an advertising campaign, citizens are encouraged to use the new "GO-D.O.T!" system and head for the nearest bus stop to be transported to and from the central city. Suppose that.
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  54.For a variable that has a standard normal distribution,   a) What is the probability that z < ?1.34?     b) What is the probability that z < +2.56?     c) What is the probability that z is between ?1.5 and +1.5.     d) What value of z separates the smaller 5% of the standard normal distribution from the larger 95%?     e) What values.
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  39.What information about a probability distribution do the mean and standard deviation of a random variable provide?       40.The sales of a newsmagazine vary from week to week, depending on the importance of the news of the previous week. From empirical data over many years, the following distribution of sales (rounded to.
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  23.Define, using your own words, a test statistic.       24.In your own words, what is a P-value?       25.As children grow they develop what is known as "representational insight," a connection between an object and a symbol for that object. A random sample of youngsters 24-months old were shown a video of someone putting.
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  41.In the study in Exhibit 5-1, passengers were also classified by age:   Discontentment Felt When Seat-mate Used Common Armrest: Males and Females by Age     Bothered Not bothered Totals Females under 40 14 10 24 Males under 40 23 2 25 Females over 40 5 16 21 Males over 40 15 16 31 Totals 57 44 101   Suppose one of these passengers was randomly selected. Calculate the probability that:   a) The passenger is under 40, given that she is.
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TRUE/FALSE   1.Two samples are said to be independent when the selection of the individuals in one sample has no bearing on the selection of those in the other sample.     2. is a biased estimator of p1 ? p2.     3.When constructing a confidence interval for the difference of two population proportions, the appropriate standard.
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  MULTIPLE CHOICE   10.You are interested in determining whether there is strong evidence in support of the claim that less than 40% of retired adults have a part-time job. To answer this question, what null and alternative hypotheses should you test?   a. versus b. versus c. versus d. versus e. versus       11.Which of.
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  26.How are the quantities, and , related?       27.Consider sampling from a population whose proportion of successes is p = 0.1. As the sample size, n, increases, some characteristics of the sampling distribution of change. Which of the following characteristics will change as n increases, and what is the nature.
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  MULTIPLE CHOICE   13.Which of the following random variables are discrete?   I). the volume of a balloon in liters II). the number of helium atoms in a balloon II). the number of balloons at a birthday party   a. I only b. II only c. III only d. II and III only e. I, II, and III       14.Which of the following random variables are continuous?   I). the air.
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