Lithium is sometimes used in the clandestine synthesis of methamphetamine, and is often found as an impurity in final product. The amount of lithium impurities in two different methamphetamine seizures were thought to be the same, but the defendant claimed the samples were different. The methamphetamine content was indistinguishable. The lithium content was analyzed using a spectrophotometric technique (ICP-OES) and the results are as follows:
Sample A: n=4, mean lithium content = 26 ppm, s.d. = 5 ppm
Sample B: n=4, mean lithium content= 40 ppm, s.d. = 8 ppm.
Perform a t-test to compare the two means at the 95% confidence level.
What is the calculated value of t (to two sig. figs)?
What is the critical value of t (to two sig. figs)?
Is the lithium content of the methamphetamine samples significantly different at the 95% confidence level?