Two brands of cigarettes are selected, and their nicotine content is compared. The data are shown below. Test the claim that the population mean nicotine in the two brands are different. Use α=.01
Brand a
X1 = 25.6 mg
σ = 5.1 mg
n1 = 30
Brand b
X2 = 32.9 mg
σ 2 = 4.4 mg
n2 = 40