APPLICATION:
an experimental study was conducted by a researcher to
determine if a new time slot has an effect on the performance
of pupils in mathematics. Fifteen randomly selected learners
participated in the study. Toward the end of the investigation, a
standardized assessment was conducted. The sample mean x̄= 75 and s=5. In standardization of the test, the mean was
65 and standard deviation was 8. Based on the evidence at
hand, is the new time slot effective? Use α = 0.05.
Difference of two independent normal variables
Let have a normal distribution with mean and variance
Let have a normal distribution with mean and variance
If and are independent, then will follow a normal distribution with mean and variance
The following null and alternative hypotheses need to be tested:
This corresponds to a two-tailed test, for which a t-test for one mean, with unknown population standard deviation, using the sample standard deviation, will be used.
Based on the information provided, the significance level is
degrees of freedom, and the critical value for a two-tailed test is
The rejection region for this two-tailed test is
The t-statistic is computed as follows:
Since it is observed that it is then concluded that the null hypothesis is rejected.
Using the P-value approach:
The p-value for two-tailed is and since it is then concluded that the null hypothesis is rejected.
Therefore, there is enough evidence to claim that the population mean is different than 0, at the significance level.
Therefore, there is enough evidence to claim that the new time slot can be effective, at the significance level.
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