404 a). A manufacturer claims that the mean lifetime of light bulbs is 250 hours of use. A sample of 20 light bulbs yielded the following data: 237,254,255,239,244,248,252,255,233,259,236,232,243,261,255,245,248,243,238,246 For the above data, the manufacturer has recorded X = 246.15 and S=8.66. [4 M] Are these data consistent, at the 5% level of significance with the claim of the manufacturer