A group of online MBA students was Interested in comparing the operating time of cordless toothbrushes manufactured by two different companies, Oral B and Philips. Group members took a random sample of 18 toothbrushes from Oral B and 15 from Philips. Each was charged overnight, and the students recorded the number of hours of use before needing to be recharged. Oral B toothbrushes operated for an average of 129.7 hours with a standard deviation of 1.74 hours; Philip's toothbrushes operated for an average of 130.6 hours with a standard deviation of 1.72 hours. The 90% confidence interval is (-1.93, 0.13). The correct interpretation of the confidence interval result is