Thunderstorm Speeds A meteorologist who sampled 7 thunderstorms found that the average speed at which they traveled across a certain state was 18 miles per hour. The standard deviation of the sample was 3.3 miles per hour. Round the final answers to at least two decimal places. Part: 0 / 2 Part 1 of 2 Find the 95% confidence interval of the mean. Assume the variable is normally distributed.