(a)

In an investigation of toxins produced by molds that infect corn crops, a biochemist prepares extracts of the mold culture with organic solvents and then measures the amount of the toxic substance per gram of solution. From 6 preparations of the mold culture, the following measurements of the toxic substance (in milligrams) are obtained: 1.4, 1.4, 1.6, 1.7, 2.1, 2.2 Find a 99% confidence interval for the mean weight (in milligrams) of toxic substance per gram of mold culture in the sampled population.