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. (UsetDistribution Table.)

Compute the 98% confidence interval for his mpg. (Round your answers to 3 decimal places.) Between __________ and __________

How many times should he fill his gas tank to obtain a margin of error below 0.15 mpg? (Round up your answer to the next whole number.) Sample Size __________