Question

For a new study conducted by a fitness magazine,

240

females were randomly selected. For each, the mean daily calorie consumption was calculated for a September-February period. A second sample of

230

females was chosen independently of the first. For each of them, the mean daily calorie consumption was calculated for a March-August period. During the September-February period, participants consumed a mean of

2385.3

calories daily with a standard deviation of

206

. During the March-August period, participants consumed a mean of

2414.7

calories daily with a standard deviation of

282.5

. The population standard deviations of daily calories consumed for females in the two periods can be estimated using the sample standard deviations, as the samples that were used to compute them were quite large. Construct a

90%

confidence interval for

−μ1μ2

, the difference between the mean daily calorie consumption

μ1

of females in September-February and the mean daily calorie consumption

μ2

of females in March-August. Then complete the table below.

Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places. (If necessary, consult a list of formulas.)

What is the lower limit of the 90% confidence interval? What is the upper limit of the 90% confidence interval?

Answer 1