Just how “decaffeinated” is decaffeinated coffee? Researchers analyzed 12 samples of two kinds of Starbucks’decaffeinated coffee. The caffeine in a cup of decaffeinated espresso had a mean 9.4 mg with...

Just how “decaffeinated” is decaffeinated coffee? Researchers analyzed 12 samples of two kinds of Starbucks’decaffeinated coffee. The caffeine in a cup of decaffeinated espresso had a mean 9.4 mg with a standard deviation of 3.2 mg, while brewed decaffeinated coffee had a mean of 12.7 mg with a standard deviation of 0.35 mg. Assuming unequal population variances, is there a significant difference in caffeine content between these two beverages at α = .01? (Based on McCusker, R. R., Journal of Analytical Toxicology 30 [March 2006], pp. 112–114.)