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State the null and alternative hypotheses that would be used to test the following claims: a. There is a difference between the mean age of employees at two different large companies. b. The mean of population 1 is greater than the mean of population 2 c. The mean yield of sunflower seeds per county in North Dakota is less than the mean yield per county in South Dakota. d. There is no difference in the mean number of hours spent studying per week between male and female college students.

Short Answer

Expert verified
For claim a, \(H_0: \mu_1 - \mu_2 = 0\) and \(H_a: \mu_1 - \mu_2 \neq 0\). For claim b, \(H_0: \mu_1 \leq \mu_2\) and \(H_a: \mu_1 > \mu_2\). For claim c, \(H_0: \mu_{ND} \geq \mu_{SD}\) and \(H_a: \mu_{ND} < \mu_{SD}\). For claim d, \(H_0: \mu_{M} = \mu_{F}\) and \(H_a: \mu_{M} \neq \mu_{F}\).

Step by step solution

01

Hypothesis for the difference between means of two companies

For claim a, the null hypothesis \(H_0\) would be that the difference between the mean ages of employees at the two companies is zero (i.e., there is no difference), thus \(H_0: \mu_1 - \mu_2 = 0\). The alternative hypothesis \(H_a\) would be that there is a difference, thus \(H_a: \mu_1 - \mu_2 \neq 0\).
02

Hypothesis for mean of population 1 is greater than population 2

For claim b, the null hypothesis \(H_0\) would be that the mean of population 1 is not greater than the mean of population 2, thus \(H_0: \mu_1 \leq \mu_2\). The alternative hypothesis \(H_a\) is the opposite of the null, thus \(H_a: \mu_1 > \mu_2\).
03

Hypothesis for mean yield of sunflower seeds per county

For claim c, the null hypothesis \(H_0\) is that the mean yield of sunflower seeds per county in North Dakota is not less than South Dakota, thus \(H_0: \mu_{ND} \geq \mu_{SD}\). The alternative hypothesis \(H_a\) would be that the mean yield in North Dakota is less than South Dakota, thus \(H_a: \mu_{ND} < \mu_{SD}\).
04

Hypothesis for mean number of studying hours between genders

For claim d, the null hypothesis \(H_0\) is that there's no difference in mean studying hours between male and female students, thus \(H_0: \mu_{M} = \mu_{F}\). The alternative hypothesis \(H_a\) would be that there is a difference, thus \(H_a: \mu_{M} \neq \mu_{F}\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Null and Alternative Hypotheses
Understanding the null hypothesis (\( H_0 \) and the alternative hypothesis (\( H_a \) is crucial when it comes to hypothesis testing in statistics. The null hypothesis is a statement that implies no effect or no difference in the context of the research question. It is the hypothesis that one seeks to test and, typically, to nullify or disprove. For example, if we're looking at whether there's a difference between two groups' means, the null hypothesis would generally state that the difference between the groups is zero.

On the contrary, the alternative hypothesis (\( H_a \) represents what a researcher wants to prove. This hypothesis suggests that there is a statistically significant effect or difference. The direction of the alternative hypothesis can be two-sided (meaning there could be any difference), greater than, or less than, depending on the research question. Referring to our textbook problems, for a claim that the mean age of employees at two companies differs, the alternative hypothesis challenges the null by suggesting a specific difference exists between their mean ages.
Mean Comparison
When comparing means between two groups, statisticians use a variety of tests to determine if the observed differences are statistically significant or if they might have occurred by chance. This process is typically conducted by calculating the means of each group and then comparing them using a formula that accounts for the variability within the groups and the size of the groups.

If we're comparing the mean yield of sunflower seeds per county between North Dakota and South Dakota, we're essentially checking if the average yield from one state is significantly different from the other. In this scenario, one would calculate the mean yield for each state individually and then determine if any observed difference is large enough to be unlikely to have arisen under the assumption that our null hypothesis of no difference is true.
Statistical Significance
Statistical significance is a term used to describe whether the results of an experiment or study are likely to be true and not occurred by chance. This concept relates to the probability that the observed effect or difference would occur if the null hypothesis were true. In hypothesis testing, this probability is known as the p-value. A low p-value (usually less than 0.05) indicates that the null hypothesis can be rejected, meaning that the findings are statistically significant and not due to random chance.

Importance of P-Value:

When determining the statistical significance, the p-value helps us make a decision about our null hypothesis. For instance, when investigating whether studying hours differ between genders, if the resulting p-value is less than our significance level (let's say 0.05), we then have evidence to reject our null hypothesis and accept the alternative hypothesis, suggesting a real difference exists.

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Most popular questions from this chapter

If a random sample of 18 homes south of Center Street in Provo has a mean selling price of \(\$ 145,200\) and a standard deviation of \(\$ 4700,\) and a random sample of 18 homes north of Center Street has a mean selling price of \(\$ 148,600\) and a standard deviation of \(\$ 5800,\) can you conclude that there is a significant difference between the selling prices of homes in these two areas of Provo at the 0.05 level? Assume normality. a. Solve using the \(p\) -value approach. b. Solve using the classical approach.

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