Chapter 9.1, Problem 15E

In Exercises 9.15–9.22, hypothesis tests are proposed. For each hypothesis test,

1. a.      determine the null hypothesis.
2. b.      determine the alternative hypothesis.
3. c.       classify the hypothesis test as two tailed, left tailed, or right tailed.

9.15 Toxic Mushrooms? Cadmium, a heavy metal, is toxic to animals. Mushrooms, however, are able to absorb and accumulate cadmium at high concentrations. The Czech and Slovak governments have set a safety limit for cadmium in dry vegetables at 0.5 part per million (ppm). M. Melgar et al. measured the cadmium levels in a random sample of the edible mushroom Boletus pinicola and published the results in the paper “Influence of Some Factors in Toxicity and Accumulation of Cd from Edible Wild Macrofungi in NW Spain” (Journal of Environmental Science and Health, Vol. B33(4). pp. 439–455). A hypothesis test is to be performed to decide whether the mean cadmium level in Boletus pinicola mushrooms is greater than the government’s recommended limit.