How long do new batteries last on a camping trip? Random sample of N subscript one equals 42 small camp flash lights were installed with brand one batteries and left on until the batteries failed. The...

 How long do new batteries last on a camping trip? Random sample of N subscript one equals 42 small camp flash lights were installed with brand one batteries and left on until the batteries failed. The sample mean lifetime was X bar equals 9.8 hours. Another sample of N subscript two equals 38 small flashlights of the same model were installed with brand two batteries and leftOn until the batteries failed. The sample mean of lifetimes was X bar subscript two equals 8.1 hours. Historical data suggests Sigma subscript one equals 2.2 hours and sigma subscript two equals 3.5 hours. Find a 90% confidence interval for the difference in battery life. Does it appear that one battery last longer than the other? Explain