Question

ch 21 ddt is a pesticide banned in the united states for its danger to humans and animals. in an experiment on the impact of ddt, six rats were exposed to ddt poisoning and six rats were not exposed. for each rat in the experiment, a measurement of nerve sensitivity was recorded. the researchers suspected that the mean nerve sensitivity for rats exposed to ddt is greater than that for rats not poisoned. let μ1 be the mean nerve sensitivity for rats poisoned with ddt. let 2 be the mean nerve sensitivity for rats not poisoned with ddt. the p - value for this test was between 0.05 and 0.01. which of the following is a reasonable conclusion? this test is unreliable because the populations were sampling from are heavily skewed. there are outliers in these data, so we cant rely on the two - sample t test. there is fairly strong evidence to support a conclusion that the mean nerve sensitivity is greater in rats exposed to ddt than in rats not exposed to ddt. there isnt much evidence to support a conclusion that the mean nerve sensitivity is greater in rats exposed to ddt than in rats not exposed to ddt.

Explanation:

Step1: Understand the P - value concept

The P - value is a measure of the evidence against the null hypothesis. A small P - value (in this case, between \(0.01\) and \(0.05\)) indicates strong evidence against the null hypothesis.

Step2: Relate P - value to the conclusion

The null hypothesis \(H_0:\mu_1\leq\mu_2\) (where \(\mu_1\) is the mean for DDT - exposed rats and \(\mu_2\) is the mean for non - exposed rats) and the alternative hypothesis \(H_a:\mu_1 > \mu_2\). Since the P - value is between \(0.01\) and \(0.05\), which is less than the common significance level of \(0.05\), we reject the null hypothesis.

Answer:

There is fairly strong evidence to support a conclusion that the mean nerve sensitivity is greater in rats exposed to DDT than in rats not exposed to DDT.