1. A magazine is considering the launch of an online edition. The magazine plans to go ahead only if it's convinced that more than 25% of the current readers would subscribe. The magazine contacted a simple random sample of 500 current subscribers and determine that 137 of those surveyed expressed an interest in the online edition.
You are writing the null and alternative hypotheses. Should you use a left-tailed, right-tailed or two-tailed HA?
A) Left-tailed
B) Right-tailed
C) Two-tailed
D) Does not make any difference
E) Unable to determine with the given information
Would this be a right-tailed?
2. The county health department has concerns about the chlorine level of 0.4% mg/mL at a local water park increasing to unsafe level. The water department tests the hypothesis that the local water park's chlorine proportions have remained the same, and find a P-value of 0.005.
Provide an appropriate conclusion.
A) There's only a 0.5% chance of seeing no change in the chlorine proportion in the results we observed from natural sampling variation. We conclude the chlorine proportion is higher.
B) We can say there is a 0.5% chance of seeing a change in the chlorine proportions in the results we observed from natural sampling variation. We conclude the chlorine proportion is higher.
C) There is a 99.5% chance of no change in the chlorine proportion.
D) We can say there is a 0.5% chance of seeing no change in the chlorine proportions in the results we observed from natural sampling variation. There is no evidence of a higher chlorine proportion, but we cannot conclude the chlorine proportion is the same.
E) There is a 0.5% chance of no change in the chlorine proportion.
Answer E?
1. More than
B
I'm confused. Are you saying # 1 is more than, which is B? Or # 1 is more than and #2 is B?
1. B
2. B
Thank you, Kuai!
Hey Michael 2 is wrong
The correct answer is A
1. To determine the null and alternative hypotheses in this scenario, we need to consider the statement and the question being asked. In this case, the magazine is considering the launch of an online edition and wants to know if more than 25% of the current readers would subscribe. So, our question is whether the proportion of subscribers interested in the online edition is greater than 25%.
The null hypothesis (H0) typically represents the status quo or no effect, while the alternative hypothesis (HA) represents the claim or effect we want to test. Since our question is whether the proportion is greater than 25%, our alternative hypothesis would state that the proportion is indeed greater than 25%.
Based on this information, we should use a right-tailed HA. A right-tailed HA is used when we want to test if the parameter is larger than a certain value (in this case, 25%).
Therefore, the answer is B) Right-tailed.
2. In this scenario, the hypothesis being tested is about the chlorine level at a local water park. The test yields a p-value of 0.005.
To interpret this p-value, we compare it to a significance level (usually denoted by α) that we set in advance. If the p-value is less than or equal to the significance level, we reject the null hypothesis (H0). Alternatively, if the p-value is greater than the significance level, we fail to reject the null hypothesis.
Based on the given information, the p-value is 0.005. However, we do not know the significance level (α) that was chosen in this hypothesis test. Without knowing the chosen significance level, we cannot definitively determine which conclusion is appropriate.
Therefore, the answer is E) Unable to determine with the given information.