6 / 26 Statistics & Estimation

McDonald's Weight IV

McDonald's claims that their Quarter Pounders are, on average, heavier than Quarter Pounders at Burger King. The true standard deviation of burger weights from each company is thought to be equal, but is unknown. To test this claim, Guy Fieri independently and randomly weighs 1515 Quarter Pounders from each company. He finds that Quarter Pounders from McDonald's and Burger King, respectively, have mean weights of 4.054.05 and 4.014.01 ounces with sample standard deviations 0.090.09 oz and 0.0850.085 oz. Test McDonald's claim at significance α=0.05\alpha = 0.05 . What should your conclusion be?

A

The test is impossible because the true standard deviations are unknown.

B

Fail to reject H0H_0; there is not enough evidence at α=0.05\alpha=0.05 that McDonald's Quarter Pounders are heavier.

C

Reject H0H_0; the sample mean difference is statistically significant at α=0.05\alpha=0.05.

D

Reject H0H_0 because 4.05>4.014.05>4.01 regardless of the variance.