Amanufacturer of new light bulbs claims the average lifetime of its long-life bulb is more than 4000 hours. to test this claim, a reputable testing firm took a random sample of 100 bulbs and life tested them. the testing firm found the average life of the sample to be 4500 hours with a sample standard deviation, s = 400 hours. the value of the test statistic for this problem isa 1.25b -1.25c 12.5d -12.5e none of the values listed