Exam 9: Sampling Distributions

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A sample of size 200 is taken at random from an infinite population.Given that the population proportion is 0.60,the probability that the sample proportion is greater than 0.58 is:

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As n gets larger,the sampling distribution of As n gets larger,the sampling distribution of   becomes increasingly bell shaped.This phenomenon is due to the ____________________. becomes increasingly bell shaped.This phenomenon is due to the ____________________.

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CFO's Salary Suppose that the starting salaries of female CFO's have a positively skewed distribution with mean of $56,000 and a standard deviation of $12,000.The starting salaries of male CFO's are positively skewed with a mean of $50,000 and a standard deviation of $10,000.A random sample of 50 female CFO's and a random sample of 40 male CFO's are selected. ​ ​ -{CFO's Salary Narrative} Find the standard error of the sample mean difference.

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An infinite population has a mean of 40 and a standard deviation of 15.A sample of size 100 is taken at random from this population.The standard error of the sample mean equals:

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Number of Fish Tanks The following data give the number of fish tanks owned for a population of 4 families.  Number of Fish Tanks  The following data give the number of fish tanks owned for a population of 4 families.   ​ ​ -{Number of Fish Tanks Narrative} Find the mean and the standard deviation for the population. ​ ​ -{Number of Fish Tanks Narrative} Find the mean and the standard deviation for the population.

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The mean of the sampling distribution of the sample proportion, The mean of the sampling distribution of the sample proportion,   ,when the sample size n = 100 and the population proportion p = 0.03,is 0.03. ,when the sample size n = 100 and the population proportion p = 0.03,is 0.03.

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Graduate Internships The chairman of the Biology department in a certain college believes that 70% of the department's graduate internships are given to international students.A random sample of 50 graduate interns is taken. ​ ​ -{Graduate Internships Narrative} What is the probability that the sample proportion  Graduate Internships  The chairman of the Biology department in a certain college believes that 70% of the department's graduate internships are given to international students.A random sample of 50 graduate interns is taken. ​ ​ -{Graduate Internships Narrative} What is the probability that the sample proportion   is between 0.65 and 0.73? is between 0.65 and 0.73?

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The standard error of the difference The standard error of the difference   is equal to the standard error of the difference   . is equal to the standard error of the difference The standard error of the difference   is equal to the standard error of the difference   . .

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In an effort to identify the true proportion of college freshman who are under 18 years of age,a random sample of 500 freshmen was taken.Fifty of them were under the age of 18.The value 0.10 is a point estimate of the true proportion of freshman under age 18.

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DVD Rental Store A DVD rental store wants to know what proportion of its customers are under age 21.A simple random sample of 500 customers was taken,and 375 of them were under age 21.Presume that the true population proportion of customers under age 21 is 0.68. ​ ​ -{DVD Rental Store Narrative} Describe the shape of the sampling distribution of proportion of customers who are under age 21.

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In a given year,the average annual salary of a NHL hockey player was $205,000 with a standard deviation of $24,500.If a simple random sample of 50 players was taken,what is the probability that the sample mean will exceed $210,000?

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If all possible samples of size n are drawn from a population,the probability distribution of the sample mean If all possible samples of size n are drawn from a population,the probability distribution of the sample mean   is called the: is called the:

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A sample of size 25 is selected from a population of size 75.The finite population correction needed to find the standard error of A sample of size 25 is selected from a population of size 75.The finite population correction needed to find the standard error of   . .

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Magazines A local magazine store sells an average of 2,100 magazines per day,with a standard deviation of 500 magazines.Consider a sample of 60 days of operation. -{Magazines Narrative} Find the expected value and the standard error of the sample mean.

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Mean Salary In order to estimate the mean salary for a population of 500 employees,the president of a certain company selected at random a sample of 40 employees. ​ ​ -{Mean Salary Narrative} Would you use the finite population correction factor in calculating the standard error of the sample mean in this case? Explain.

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Suppose it is known that 60% of radio listeners at a particular college are smokers.A sample of 500 students from the college is selected at random.Approximate the probability that at least 280 of these students are radio listeners.

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Consider an infinite population with a mean of 160 and a standard deviation of 25.A random sample of size 64 is taken from this population.The standard deviation of the sample mean equals:

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What is the probability that you get more than 200 heads if you flip a coin 400 times?

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If the population distribution is unknown,in most cases the sampling distribution of the mean can be approximated by the normal distribution if the samples contain at least 30 observations.

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Average Annual Revenue Suppose that the average annual revenue of a small business is $150,000 with a standard deviation of $40,000.Assume that the revenue distribution is normal. ​ ​ -{Average Annual Revenue Narrative} Why are your answers to the previous two questions different?

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