Is there significant evidence at the 5% level that conductors consume more calories per day than do drivers ...

Do various occupational groups differ in their diets? A British study of this question compared 85 drivers and 58 conductors of London double-decker buses. The conductors' jobs require more physical activity. The article reporting the study gives the data as "Mean daily consumption ± (se)." Some of the study results appear below.

Drivers

Conductors

Total calories

2822 ± 14

2850 ± 18

Alcohol (grams)

0.22 ± 0.11

0.35 ± 0.04

(a) Is there significant evidence at the 5% level that conductors consume more calories per day than do drivers? Use the conservative two-sample t method to find the t-statistic, and the degrees of freedom. (Round your answer for t to three decimal places.)

t =

df =

b) Give a 95% confidence interval for the mean daily alcohol consumption of London double-decker bus conductors. (Round your answers to three decimal places.)

c) Give a 99% confidence interval for the difference in mean daily alcohol consumption for drivers and conductors. (conductors minus drivers. Round your answers to three decimal places.)