Spreading rate of spilled liquid. Refer to the Chemical Engineering Progress (January 2005) study of the rate at which a spilled volatile liquid will spread across a surface, Exercise 11.30 (p. 662). Recall that simple linear regression was used to model y = mass of the spill as a function of x = elapsed time of the spill.

a. Find a 99% confidence interval for the mean mass of all spills with an elapsed time of 15 minutes. Interpret the result.

b. Find a 99% prediction interval for the mass of a single spill with an elapsed time of 15 minutes. Interpret the result.

c. Compare the intervals, parts a and

b. Which interval is wider? Will this always be the case? Explain.