Thunderstorm Speeds A meteorologist who sampled 6 thunderstorms found that the average speed at which they traveled across a certain state was 15 miles per hour. The standard deviation of the sample was 3.1 miles per hour. Round the final answers to at least two decimal places. Part: 0/2 Part 1 of 2 Find the 90% confidence interval of the mean. Assume the variable is normally distributed.