A light bulb manufacturer wants to compare the mean lifetimes of two of its light bulbs, model A and model B. Independent random samples of the two models were taken. Analysis of 9 bulbs of model A showed a mean lifetime of 1305 hours and a standard deviation of 92 hours. Analysis of bulbs of model B showed a mean lifetime of hours and a standard deviation of hours. Assume that the populations of lifetimes for each model are normally distributed and that the variances of these populations are equal. Construct a confidence interval for the difference between the mean lifetime of model A bulbs and the mean lifetime of model B bulbs. Then find the lower limit and upper limit of the confidence interval.