A reporter bought hamburgers at randomly selected stores of two different restaurant chains, and had the number of Calories in each hamburger measured. Can the reporter conclude, at a= 0.05, that the hamburgers from the two chains have a different number of Calories? (Show all the five steps)

Chain A Chain B

Sample Size 7 8

Sample mean 280 cal. 315 cal.

Sam. std. dev. 20 cal 30 cal