Tchebysheff's Theorem states that the percentage of measurements in a data set that fall within three standard deviations of their mean is:
a. 75
b. 68
c. 16
d. at least 89
e. at most 80
Q. 2Which of the following statements is false?
a. When comparing two populations, we need two samples, one from each population.
b. If the same set of sources or related sets are used to obtain the data representing two populations, we have dependent samples.
c. If two unrelated sets of sources are used to obtain the data representing two populations, one set from each population, we have independent samples.
d. None of the above
Q. 3From a sample of size 100, the following descriptive measures were calculated: median = 23, mean = 20, standard deviation = 5, range = 35; seventy-five sample values are between 10 and 30; and ninety-nine sample values are between 5 and 35 . If you knew the sample mean, median, and standard deviation were correct, which one of the following conclusions might you draw?
a. The distribution is skewed to the right because the median exceeds the mean.
b. The range must have been calculated incorrectly because it should not be seven times the standard deviation's value.
c. The number of sample values between 10 and 30 was miscounted.
d. The number of sample values between 5 and 35 must have been miscounted because all 100 values must be in this interval.
e. All of these.
Q. 4If two samples have the same size, the samples must be dependent.
Indicate whether the statement is true or false
Q. 5A college placement office conducted a survey of 100 engineers who had graduated from Stanford University. For these engineers, the mean salary was computed to be 72,000 with a standard deviation of 8,000 . The percentage of these engineers who earn more than 96,000 or less than 48,000 is:
a. approximately 0
b. at least 5.6 (1/18 of the engineers)
c. at most 5.6 (1/18 of the engineers)
d. at most 11.1 (1/9 of the engineers)
e. at least 11.1 (1/9 of the engineers)
Q. 6Independent samples are obtained by using unrelated sets of subjects.
Indicate whether the statement is true or false
Q. 7The distribution of credit card balances for customers is highly skewed to the right with a mean of 1,200 and a standard deviation of 150 . Based on this information, approximately 68 of the customers will have credit card balances between 1,050 and 1,350.
Indicate whether the statement is true or false
Q. 8Two dependent samples may have different sample sizes.
Indicate whether the statement is true or false
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