Question

Make your own datafile (or type the data values in MINITAB spreadsheet) and answer the below questions by the five steps for test of hypothesis. Also include the output from MINITAB results if necessary. Submit your printed copy before the class.

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.”^** Here are data.

CADMIUM

0.24

0.59

0.62

0.16

0.77

1.33

0.92

0.19

0.33

0.25

0.59

0.32

Using P-value approach, perform a test of hypothesis at the 10% significance level, whether the mean cadmium level of Boletus pinicola mushrooms is greater than the government’s recommended limit of 0.5 ppm? Assume that the population standard deviation of cadmium levels in Boletus pinicola mushrooms is 0.3 ppm. ^** Journal of Environmental Science and Health, Vol. B33(4), pp. 439-455

Answer 1

Hence we conclude that there is insufficient evidence that the mean cadmium level of Boletus pinicola mushrooms is greater than the government’s recommended limit of 0.5 ppm.

Minitab output:

One-Sample Z: CADMIUM

Test of mu = 0.5 vs > 0.5
The assumed standard deviation = 0.3

                                       90% Lower
Variable        N    Mean   StDev SE Mean      Bound     Z      P
CADMIUM   12 0.5258 0.3521   0.0866       0.4148 0.30 0.383