Dylan Jones kept careful records of the fuel efficiency of his new car. After the first eight times he filled up the tank, he found the mean was 21.3 miles per gallon (mpg) with a sample standard deviation of 0.8 mpg.

1. Compute the 98% confidence interval for his mpg. (UsetDistribution Table.)(Round your answers to 3 decimal places.)
2. How many times should he fill his gas tank to obtain a margin of error below0.15 mpg? (UsezDistribution Table.)(Round your answer to the next whole number.)