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20 Cards in this Set
- Front
- Back
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The following data was collected from a simple random sample from a process (an infinite population).
13 15 14 16 12 Refer to Exhibit 7-1. The mean of the population (Hint: page 16 of ppt file) a.) is 14 b.) is 15 c.) is 15.1581 d.) could be any value |
d.) could be any value |
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A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are a.) 500 and 0.047 b.) 500 and 0.050 c.) 0.5 and 0.047 d.) 0.5 and 0.050 |
The standard deviation of sample proportion, aka standard error of proportion is: square root (0.5 * 0.5/100) = d.)0.5 and 0.050 |
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As the sample size increases, the... a.) standard deviation of the population decreases b.) population mean increases c.) standard error of the mean decreases d.) standard error of the mean increases |
c.) standard error of the mean DECREASES |
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A random sample of 150 people was taken from a very large population. Ninety of the people in the sample were females. The standard error of the proportion of females is
a.) 0.0016 b.) 0.2400 c.) 0.1600 d.) 0.0400 |
d.) 0.0400 |
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The following data was collected from a simple random sample from a process (an infinite population).
13 15 14 16 12 Refer to Exhibit 7-1. The point estimate of the population standard deviation is (Hint: page 16 of ppt file) a.) 2.500 b.) 1.581 c.) 2.000 d.) 1.414 |
b.) 1.581 |
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A sample of 25 observations is taken from a process (an infinite population). The sampling distribution of p (with a line on top) is...
a.) not normal since n < 30 b.) approximately normal because p (with a line on top) is always normally distributed c.) approximately normal is np > 5 and n(1-p)>5 d.) approximately normal if np>30 and n(1-p)>30 |
c.) approximately normal if np>5 and n(1-p)>5 |
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A population has a mean of 80 and a standard deviation of 7. A sample of 49 observations will be taken. The probability that the mean from that sample will be larger than 82 is...
a.) 0.5228 b.)0.9772 c.) 0.4772 d.) 0.0228 |
Type B question. the z-score of 82 = (82-80)/(7/square root of 49) = 2, on z table Pr(z<2) = 0.9772, so the probability bigger than 82 = 1- 0.9772 = 0.0228 |
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Four hundred registered voters were randomly selected asked whether gun laws should be changed. Three hundred said "yes," and one hundred said "no."Refer to Exhibit 7-2. The point estimate of the proportion in the population who will respond "yes" is (Hint: page 16 of ppt file)
a.) 300 b.) approximately 300 c.) 0.75 d.) 0.25 |
c.) 0.75 |
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_______ is a property of a point estimator that is present when the expected value of the point estimator is equal to the population parameter it estimates.
a.) predictible b.) precise c.) symmetric d.) unbiased |
d.) unbiased |
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A sample of 51 observations will be taken from a process (an infinite population). The population proportion equals 0.85. The probability that the sample proportion will be between 0.9115 and 0.946 is
a.) 0.8633 b.) 0.6900 c.) 0.0819 d.) 0.0345 |
c.) 0.0819 |
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7-5. Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8.Refer to Exhibit 7-5. The mean and the standard deviation of the sampling distribution of the sample means are
a.) 8.7 and 1.94 b.) 36 and 1.94 c.) 36 and 1.86 d.) 36 and 8 |
c.) 36 and 1.86 |
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A population has a mean of 53 and a standard deviation of 21. A sample of 49 observations will be taken. The probability that the sample mean will be greater than 57.95 is...
a.) 0 b.) 0.0495 c.) 0.4505 d.) None of the alternative answers is correct |
Type B question. the z-score of 57.95 = (57.95 - 53)/(21/square root of 49)=1.65, on z table Pr (z<1.65) = 0.9505, so the probability bigger than 57.95 = 1 - 0.9505 = b.) 0.0495 |
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The following data was collected from a simple random sample from a process (an infinite population).
13 15 14 16 12 7-1. The point estimate of the population mean (Hint: page 16 of ppt file) a.) is 5 b.) is 14 c.) is 4 d.) cannot be determined because the population is infinite |
b.) is 14 |
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Imagine we are trying to sell to a customer who demands that the mean of a random sample of 64 bulbs lasts at least 2,050 hours before they will buy. The population mean = 2,000 hours, and the population standard deviation is 100 hours. What mean length of bulb life could you be 90% confident that the sample mean will be at least that long? (Use the Standard Normal Cumulative Probability Table. Round to nearest integer)
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First, it is a type D question since it asks you the cutoff point where 90% of time that a random variable is bigger than a number, i.e. 10% to the left. Using the z-table, we can see that the z-value is -1.285, or -1.282 using computer. Giving z-value, we use cutoff value=mean+std.dev*z-value to find out the cutoff. Here mean is 2000, the std. dev of 64 samples is std.dev of the whole population divided by square root of sample size, which is 100/square root of 16. You will get the answer of 1984. The correct answer is: 1984 |
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The fact that the sampling distribution of the sample mean can be approximated by a normal probability distribution whenever the sample size is large is based on the
a.) central limit theorem b.) fact that there are tables of areas for the normal distribution c.) assumption that the population has a normal distribution d.) all of these answers are correct |
a.) central limit theorem |
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The sampling distribution of the sample mean... a.) is the probability distribution showing all possible values of the sample mean b.) is used as a point estimator of the population mean u (symbol) c.) is an unbiased estimator d.) shows the distribution of all possible values of u(symbol) |
a.) is the probability distribution showing ALL possible values of the sample mean |
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The standard deviation of all possible x(line on top) values is called the... a.) standard error or proportion b.) standard error of the mean c.) mean deviation d.) central variation |
b.) standard error of the mean |
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A population has a mean of 180 and a standard deviation of 24. A sample of 64 observations will be taken. The probability that the mean from that sample will be between 183 and 186 is
a.) 0.1359 b.) 0.8185 c.) 0.3413 d.) 0.4772 |
the z value for 183=(183-180)/(24/sqrt(64))=1, the z value for 186 is 2. On z table: Pr(z<1)=0.8413; Pr(z<2)=0.9772. The difference is the probability between 183 and 186.The correct answer is:
a.) 0.1359 |
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A sample of 400 observations will be taken from a process (an infinite population). The population proportion equals 0.8. The probability that the sample proportion will be greater than 0.83 is...
a.) 0.4332 b.)0.9332 c.)0.0668 d.) 0.5668 |
c.) 0.0668 |
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The standard deviation of p(line atop) is referred to as the a.) standard proportion b.) sample proportion c.) average proportion d.) standard error of the proportion |
d.) standard error of the proportion |
