2. Weight of a rock: In a geology course, students are learning to use a balance

Question

2. Weight of a rock: In a geology course, students are learning to use a balance scale to accurately weigh rocks. One student plans to weigh a rock 20 times and then calculate the average of the 20 measurements to estimate her rock's true weight. A second student plans to weigh a rock 5 times and calculate the average of the 5 measurements to estimate his rock's true weight. The student who weighs his rock 5 times uses the mean to calculate the 95% confidence interval for the rock weight (in grams). His interval is (25.2, 29.1). What does a 95% confidence interval for rock weight tell us in this case? A.We are 95% confident that this interval includes the mean of the 5 weight measurements taken by this student. B.We are 95% confident that most rocks of this type weigh between 25.2 g and 29.1 g. C.We are 95% confident that the true weight of the rock is between 25.2 g and 29.1 g.

3. A medical researcher wants to measure the effects of a new drug on cholesterol levels using a hypothesis test. The target is a 30-point decrease in cholesterol levels after a treatment cycle. The researcher takes a random sample of patients and measures their cholesterol levels before and after a treatment cycle of the drug. Which type of hypothesis test should they use? A.test for one population proportion B.test for one population mean C.test for a difference in two population proportions D.test for a difference in two population means

Explanation / Answer

2. 95% Confidence interval gives us the range of values defined such that there is 95% probability that value of population parameter will lie in it.

Hence answer is C.We are 95% confident that the true weight of the rock is between 25.2 g and 29.1 g.

3.Here we can see that data is paired. Which means it is from the same population.

So C and D can't be answer

Now this is not the case of proportion but here we need to check difference between mean before and after the treatment.

So answer is B. Test for one population mean.

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