The director of admissions at the University of Maryland, University
College is concerned about the high cost of textbooks for the
students each semester. A sample of 25 students enrolled in the
university indicates that x(bar) = $315.40 and s = $75. (Note the
sample standard deviation is different from the first part).
A mean that is in a confidence interval is not rejected by the
confidence interval, and we say the evidence against the mean is not
significant. At the 0.05 level of significance, is there evidence against
mean $300?
Question options:
No, because 300 is below the lower limit of the confidence interval
Yes, because 300 is below the lower limit of the confidence interval
No, because 300 is in the confidence interval
Yes, because 300 is in the confidence interval

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7 / 7 points
Explain the difference between parts A and C. In both parts we are
asked whether or not there is evidence that the population mean was
over $300.
In part A: x(bar) = $315.40; s = $43.2; Sample size = 25
In part C: x(bar) = $315.40; s = $75; Sample size = 25

The larger standard deviation adds uncertainty in the sample. The sample may have had some outliers.
The smaller standard deviation adds uncertainty in the sample. The sample may have had some outliers.
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100 / 100 - 100 %
100 / 100 - 100 %
Done