A light bulb manufacturer wants to compare the mean

Last updated: 6/14/2023

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 1358 hours and a standard deviation of 107 hours Analysis of 15 bulbs of model B showed a mean lifetime of 1369 hours and a standard deviation of 114 hours Assume that the populations of lifetimes for each model are normally distributed and that the variances of these populations are equal Construct a 95 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 95 confidence interval Carry your intermediate computations to at least three decimal places Round your responses to at least two decimal places If necessary consult a list of formulas Lower limit Upper limit X S EEN