R-assignment (with part 1 and 2)
cadmium, a heavy metal, is toxic to animals. mushrooms, however, are able to absorb and accumulate cadmium at high concentrations. the czech and slovac 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 size 12 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 the data: 0.24, 0.59, 0.62, 0.16, 0.77, 1.33, 0.92, 0.19, 0.33, 0.25, 0.59, 0.32 at the 5% significance level do the data provide sufficient evidence to conclude that the mean cadmium level in boletus pinicola mushrooms differ than the government’s limit of 0.5 ppm?
1) assume that population standard deviation is known and equal to 0.37 ppm and so apply one mean-z test through r.
2) assume that population standard deviation is unknown and sample standard deviation must be used as an estimate to population standard deviation and so apply one mean-t test through r.