An article in Fire Technology investigated two different foam-expanding agents that can be used in the nozzles of fire fighting equipment. A random sample of five observation with an aqueous film-forming foam had a sample mean of 4.7 and a standard deviation of 0.6. A random sample of five observations with alcohol-type concentrates had a sample mean of 6.9 and a standard deviation of 0.8.Assume that both populations are well represented by normal distributions with the same standard deviations.

a. Find a 95% confidence interval on the difference in mean foam expansion of these two agents.

b. Based on the confidence interval, is there evidence to support the claim that there is no difference in mean foam expansion of these two agents?