Given that null hypothesis is true. "H_0: \\mu=1"
Let "\\mu=1" be the population mean and "\\sigma=10" be the population standard deviation.
The sampling distribution of the mean will have:
the mean "\\mu_{\\overline{X}}" :
the variance "\\sigma_{\\overline{X}}^2":
The standard error of the mean is
Since the sample size "n=25<30", we use t-score.
A test statistic is given by
where "\\overline{X}" is the sample mean, "\\mu" is the value of the population mean in the null hypothesis, "s" is the sample standard deviation, and "n" is the sample size.
"H_0: \\mu=1, H_1: \\mu<1".
For this left-tailed test (lower-tail test) and "\\alpha=0.10, n=25", the critical value will be
The critical region will be to the left of -1.3178:
We reject the null hypothesis if "\\overline{X}<-1.6356."
If the sample mean is -2, then
compute the p-value for the left-tailed test with 25−1 degrees of freedom:
"=P(T\\leq-1.5, df=25-1)=0.0733"
"p-value=0.0733" or "7.33 \\%" .
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