A graphing calculator of a certain type would function on average for 720 hours after it is fully charged. The company that produces these calculators are interested in determining if the functioning time is actually less than 720 hours so that they can make changes to the production design. A random sample of 41 calculators resulted in a sample mean of x = 702 and a sample standard deviation s = 100. Assume that the functioning time is normally distributed. Is there sufficient evidence for the company to change the production design? A hypothesis test with a significance level = 0.15.