In 2001, the mean household expenditure for energy was $1493, according to data obtained from the U.S. Energy Information Administration. An economist wanted to know whether this amount has changed significantly from its 2001 level. In a random sample of 35 households, he found the mean expenditure (in 2001 dollars) for energy during the most recent year to be $1628, with standard deviation $321. Test to determine if the current mean expenditure for energy is higher than in 2001 (in 2001 dollars) and the 05 significance level.
Construct a 95% confidence interval about the mean energy expenditure. What does the interval imply?