Adam tabulated the values for the average speed on each day of his road trip as 60.5, 63.2, 54.7, 51.6, 72.3, 70.7,
67.2, and 65.4 mph.
If Adam wanted to construct a one-sample t-statistic, what would the value for the
...
Adam tabulated the values for the average speed on each day of his road trip as 60.5, 63.2, 54.7, 51.6, 72.3, 70.7,
67.2, and 65.4 mph.
If Adam wanted to construct a one-sample t-statistic, what would the value for the degrees of freedom be?
4
7
9
8
RATIONALE
The degrees of freedom for a 1 sample t-test are df=n-1 where n is the sample size. In this case, n=8, then df =
n-1 = 8-1 = 7.
CONCEPT
T-Tests
2
9/18/2020 Sophia :: Welcome
https://strayer.sophia.org/spcc/introduction-to-statistics-2/milestone_take_feedbacks/6219912 2/22
Steven measures the weight of a random sample of 49 basset hounds. The mean weight was 45.8 pounds, with a
standard deviation of 3 pounds. Using the alternative hypothesis that μ < 45.8, Steven found a z test statistic of
-1.5.
What is the p-value of the test statistic? Answer choices are rounded to the thousandths place.
0.067
0.147
0.134
0.055
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RATIONALE
If we go to the chart and the row for the z-column for -1.5 and then the column 0, this value corresponds to
0.0668 or 0.067.
CONCEPT
How to Find a P-Value from a Z-Test Statistic
3
Sukie interviewed 125 employees at her company and discovered that 21 of them planned to take an extended
vacation next year.
What is the standard error of the sample proportion? Answer choices are rounded to the thousandths
place.
0.080
0.015
0.532
0.033
RATIONALE
We can note the SE of the proportion is
square root of fraction numerator p with hat on top q with hat on top over denominator n end fraction end root
.
If we note that , which means .
So if we take all this information we can note SE = .
CONCEPT
Calculating Standard Error of a Sample Proportion
4
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https://strayer.sophia.org/spcc/introduction-to-statistics-2/milestone_take_feedbacks/6219912 4/22
For a left-tailed test, the critical value of z so that a hypothesis test would reject the null hypothesis at
10% significance level would be __________. Answer choices are rounded to the hundredths place.
-1.03
-1.65
-2.33
-1.28
RATIONALE
Recall that when a test statistic is smaller than in a left tailed
test we would reject Ho. If we go to the standard normal chart and use 10% or 0.10, we will search for the
closest value to 10% as closely as possible.
0.1003 corresponds with a z-score of -1.28.
CONCEPT
How to Find a Critical Z Value
5
Edwin conducted a survey to find the percentage of people in an area who smoked regularly. He defined the
label “smoking regularly” for males smoking 30 or more cigarettes in a day and for females smoking 20 or
more. Out of 635 people who took part in the survey, 71 are labeled as people who smoke regularly.
Edwin wishes to construct a significance test for his data. He finds that the proportion of chain smokers
nationally is 14.1%.
What is the z-statistic for this data? Answer choices are rounded to the hundredths place.
-2.34
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