text: stats question? production manager is checking to see whether a difference exists between the average production levels of the day and night shifts. for the two shifts, he selects independent random samples of 15  days' production. the numbers of units produced by each shift per day are as follows: day 250 269 264 246 252 253 244 257 255 245 255 244 245 249 256  night 252 241 251 239 251 259 243 258 261 251 253 248 233 251 241 is there a significant difference between the two shifts? interpret the results that follow: 95%ci for mu1 - mu2: (-2.55, 2.49)      a. we are 95% confident that there is no difference in average production levels for day and night shifts.   b. the day shift has significantly higher average production level than the night shift, at the 95% confidence level.   c. the night shift has significantly higher average production level than the day shift, at the 95% confidence level. sum of day = 3784  sum of night = 3732  avg day = 252.266666_  avg night = 248.8  avg night ----------   = .986258 > .95  avg day  answer a.