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Study Resources (Statistics)

    61.The notation for the standard deviation of the sampling distribution of the sample mean is __________.    A.     B.σx   C.     D.μ         62.The sampling distribution of the sample mean is a normal distribution for ________ sample sizes, regardless of the shape of the corresponding population distribution.    A.Random   B.Large   C.Larger than 50   D.Small         63.A theorem that allows us to use the normal probability.
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144.When sample size is 11, find t.025.          145.When sample size is 16, find t.025.          146.When sample size is 20, find t.001.          147.When sample size is 11, find t.001.          148.When sample size is 16, find t.001.          149.The coffee and soup machine at the local bus station is supposed to fill cups with 6 ounces of soup..
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    81.Consider a normal population with a mean of 10 and a variance of 4. Find P(X > 7).    A..0668   B..9332   C..8413   D..1587       82.Consider a normal population with a mean of 10 and a variance of 4. Find P(X > 18).    A.1.00   B.0.00   C..9772   D..0228       83.Consider a normal population with a mean of 10 and a variance of 4. Find P(X.
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  True / False Questions  1.A uniform distribution f(x) is a continuous probability distribution, which says the probability that x is in any 2 intervals of equal length is the same.  TRUE       2.The mean and median are the same for a normal distribution.  TRUE       3.The mean and median are the same for an exponential distribution.  FALSE Mean and.
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    118.The weight of a product is measured in pounds. A sample of 50 units is taken from a batch. The sample yielded   = 75 lbs., and we know that σ2 = 100 lbs. Calculate a 95 percent confidence interval for μ.    A.[71.25, 78.75]   B.[72.23, 77.77]   C.[47.28, 102.72]   D.[72.67, 77.33]       119.The weight of a product is.
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    41.When a confidence interval for a population proportion is constructed for a sample size n = 30 and the value of   = .4, the interval is based on:    A.The z distribution.   B.The t distribution.   C.The exponential distribution.   D.The Poisson distribution.   E.None of these.         42.There is little difference between the values of tα/2 and zα/2 when:    A.The sample.
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148.The US local airport keeps track of the percentage of flights arriving within 15 minutes of their scheduled arrivals. The stem-and-leaf plot of the data for one year is below.  Compute the standardized quartile value Oi for i = 4.          149.The US local airport keeps track of the percentage of flights arriving.
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    41.__________ sampling is defined as sampling where we know the chance that each element in the population will be included in the sample.    A.Judgment   B.Convenience   C.Nonrandom   D.Probability         42.A Yes or No question is _____________.    A.Dichotomous   B.Multiple choice   C.Open-ended   D.Systematic         43._____________ occurs when some population elements are excluded from the process of selecting the sample.    A.Nonresponse   B.An error of observation   C.Undercoverage   D.Sampling error         44._____________ is the.
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    51.Whenever the population has a normal distribution, the sampling distribution of   is normal or near normal distribution:    A.For only large sample sizes.   B.For only small sample sizes.   C.For any sample size.   D.For only samples of size 30 or more.         52.If a population distribution is known to be normal, then it follows that:    A.The sample mean must.
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    128.If the 95 percent confidence interval for a mean is from .771 to 1.629, can we conclude that μ = .5, using a 95 percent confidence interval?    A.Yes   B.No       129.A PGA (Professional Golf Association) tournament organizer is attempting to estimate the average number of strokes for the 13th hole on a given golf.
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    31.If p = .1 and n = 5, then the corresponding binomial distribution is ____________.    A.Right skewed   B.Left skewed   C.Symmetric   D.Bimodal         32.If p = .5 and n = 4, then the corresponding binomial distribution is ____________.    A.Right skewed   B.Left skewed   C.Symmetric   D.Bimodal         33.The requirement that the probability of success remains constant from trial to trial is a property of the.
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    91.The weight of a product is normally distributed with a mean of four ounces and a variance of .25 squared ounces. What is the probability that a randomly selected unit from a recently manufactured batch weighs more than 3.75 ounces?    A..3085   B..6915   C..1587   D..8413       92.The weight of a product is normally distributed with a mean.
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    51.The number of standard deviations that a value x is from the mean is a(n) ____________.    A.Variance   B.Exponential value   C.z score   D.Area         52.The area under the curve of a valid continuous probability distribution must ____________.    A.Equal 1   B.Be between 0 and 1   C.Be infinite   D.Be less than 1         53.Given that X is a normal random variable, the probability that a.
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    71.A study conducted by a local university found that 25 percent of college freshmen support increased spending on environmental issues. If 6 college freshmen are randomly selected, find the probability that fewer than 4 support increased spending on environmental issues.    A..0330   B..7844   C..9624   D..9954       72.A study conducted by a local university found that 25 percent.
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    98.A sample set of weights in pounds are 1.01, .95, 1.03, 1.04, .97, .97, .99, 1.01, and 1.03. Assume the population of weights is normally distributed. Find a 99 percent confidence interval for the mean population weight.    A.[.965, 1.035]   B.[.969, 1.031]   C.[.973, 1.027]   D.[.941, 1.059]       99.A sample of 12 items yields   = 48.5 grams and.
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    31.The width of a confidence interval will be:    A.Narrower for 98 percent confidence than for 90 percent confidence.   B.Wider for a sample size of 64 than for a sample size of 36.   C.Wider for a 99 percent confidence than for 95 percent confidence.   D.Narrower for a sample size of 25 than for a sample.
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    11.The Central Limit Theorem states that as sample size increases, the population distribution more closely approximates a normal distribution.          12.If a population is known to be normally distributed, then it follows that the sample standard deviation must equal σ.    Sample standard deviation is calculated as σ/√n.       13.If the sampled population is exactly normally.
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    108.In a study of 265 subjects, the average score on the examination was 63.8 and s = 3.08. What is a 95 percent confidence for μ?    A.[63.59, 64.01]   B.[57.76, 69.84]   C.[63.43, 64.17]   D.[63.56, 64.04]       109.Given the following test scores, find a 95 percent confidence interval for the population mean: 148, 154, 158, 160, 161, 162,.
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    51.If everything else is held constant, decreasing the margin of error causes the required sample size to ____________.    A.Stay the same   B.Decrease   C.Increase         52.A confidence interval for the population mean is an interval constructed around the ____________.    A.Sample mean   B.Population mean   C.z test statistic   D.t test statistic         53.In determining the sample size to estimate a population proportion, as p.
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    61.The manager of the local grocery store has determined that, on average, 4 customers use the service desk every half-hour. Assume that the number of customers using the service desk has a Poisson distribution. What is the probability that during a randomly selected half-hour period, exactly 2 customers use the.
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    71.A random sample of size 1,000 is taken from a population where p = .20. Describe the sampling distribution of   .    A.Cannot be determined   B.Approximately normal   C.Skewed to the left   D.Skewed to the right         72.Find P(  < 35) if μ = 40, σx = 16, n = 16.    A..9944   B..4483   C..5517   D..1056     73.A PGA (Professional Golf Association) tournament organizer is attempting.
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    21.The mean of the sampling distribution of   is always equal to the mean of the sampled population.          22.The sampling distribution of the sample mean is developed by repeatedly taking samples of size n and computing the sample means and reporting the resulting sample means in the form of a probability distribution.          23.If.
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    101.The population of lengths of aluminum-coated steel sheets is normally distributed with a mean of 30.05 inches and a standard deviation of 0.3 inches. What is the probability that the average length of a steel sheet from a sample of 9 units is more than 29.95 inches long?    A..4602   B..8413   C..1587   D..5397       102.The chief chemist.
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    88.A botanist measures the heights of 16 seedlings and obtains a mean and standard deviation of 72.5 cm and 4.5 cm, respectively. Find the 95 percent confidence interval for the mean height of seedlings in the population from which the sample was selected.    A.[62.91, 82.09]   B.[70.30, 74.70]   C.[70.10, 74.90]   D.[70.54, 74.46]   E.[71.90, 73.10]       89.On a standard.
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    121.A manufacturer of personal computers tests competing brands and finds that the amount of energy they require is normally distributed with a mean of 285 kwh and a standard deviation of 9.1 kwh. If the lowest 25 percent and the highest 30 percent are not included in a second round.
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    51.Which of the following statements about the binomial distribution is not correct?    A.Each trial results in a success or failure.   B.Trials are independent of each other.   C.The probability of success remains constant from trial to trial.   D.The random variable of interest is continuous.   E.The experiment consists of n identical trials.         52.If n = 15 and p.
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    111.Suppose that the times required for a cable company to fix cable problems in the homes of its customers are uniformly distributed between 40 minutes and 65 minutes. What is the probability that a randomly selected cable repair visit falls within 2 standard deviations of the mean?    A.0.75   B.1.00   C.0.58   D.0.86       112.Suppose that the waiting.
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    31.Stratification can at times be combined with multistage cluster sampling to develop an appropriate sample.          32.In systematic sampling, the first element is randomly selected from the first (N/n) elements.          33.Sampling error occurs because of incomplete information.          34.The target population is the result of sampling from the original population that is of interest to.
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    41.The binomial distribution is characterized by situations that are analogous to    A.Drawing balls from an urn.   B.Coin tossing.   C.Counting defects on an item.   D.Measuring the length of an item.         42.Two characteristics, or assumptions, of the Poisson distribution are:    A.The probability of success remains constant from trial to trial, and the random variable of interest is continuous.   B.The.
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121.A manufacturing company measures the weight of boxes before shipping them to the customers. If the box weights have a population mean and standard deviation of 90 lbs. and 24 lbs., respectively, then based on a sample size of 36 boxes, what is the probability that the average weight of.
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    138.Unoccupied seats on flights cause airlines to lose revenue. Suppose a large airline wants to estimate its average number of unoccupied seats per flight over the past year. 225 flight records are randomly selected and the number of unoccupied seats is noted, with a sample mean of 11.6 seats and.
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    71.The life of a light bulb is exponentially distributed with a mean of 1,000 hours. What is the probability that the bulb will last more than 1,200 hours?    A..3012   B..3679   C..4345   D..6988       72.The life of a light bulb is exponentially distributed with a mean of 1,000 hours. What is the probability that the bulb will.
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  True / False Questions  1.The t distribution always has n degrees of freedom.    Degrees of freedom are n - 1.       2.When the margin of error is added to and subtracted from the sample mean, an interval is formed that will contain μ with a probability of (1 - α).          3.The standard error of the.
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  True / False Questions  1.If we have a sample size of 100 and the estimate of the population proportion is .10, we can estimate the sampling distribution of   with a normal distribution.          2.A sample size of 500 is sufficiently large to conclude that the sampling distribution of   is a normal distribution, when.
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    91.A random sample of size 36 is taken from a population with mean 50 and standard deviation 5. Find P(  < 51.5).    A..9641   B..0359   C..1389   D..9999       92.A random sample of size 1,000 is taken from a population where p = .20. What is   ?    A..006   B..20   C..02   D..16       93.A random sample of size 1,000 is taken from a population where p.
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    11.A continuous probability distribution having a rectangular shape, where the probability is evenly distributed over an interval of numbers, is called a uniform probability distribution.  TRUE       12.The exponential probability distribution is based on a continuous random variable.  TRUE       13.The mean of a standard normal distribution is always equal to 1.  FALSE Mean of a standard normal.
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    21.A tolerance interval is meant to contain a specified percentage of the individual population measurements.          22.A confidence interval for the population mean is meant to contain a specified percentage of the individual population measurements.    This is the definition of a tolerance interval. A confidence interval is the level of confidence we have.
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