v A purchasing manager for a large university is investigating which brand of LCD projector to purchase to equip "smart" classrooms. Of major concern is the longevity of the light bulbs used in the projectors. The purchasing manager has narrowed down the choice of projector to two brands, Infocus and Proxima, and wishes to determine if there is any difference between the two brands in the mean lifetime of the bulbs used. The purchasing manager obtained twelve projectors of each brand for testing over the last several academic terms. The number of hours the bulbs lasted on each of the twelve machines is given in the table. Lifetimes of light bulbs (hours) Infocus 894, 807, 1008, 879, 883, 691, 770, 809, 1255, 709, 1009, 679 Proxima 809, 845, 913, 751, 851, 1236, 812, 614, 589, 848, 703, 768 I Send data to calculator v) (Send data to Excel) Assume that the two populations of lifetimes are normally distributed and that the population variances are equal. Can we conclude, at the 0.01 level of s_ignificance, that the mean lifetime of light bulbs in Infocus projectors, pl, differs from Hz, the mean lifetime of light bulbs in Proxima projectors? Perform a twotailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specied in the table. (If necessary, consult a list of formulas.)