A new energy drink is supposed to improve a person’s time in the one mile run. The times, in seconds, of eight runners with and without the drink are given below:
Runner 1 2 3 4 5 6 7 8
x-time (before) 254 276 276 265 271 273 268 281
y-time (after) 265 269 277 279 266 273 275 279
Find the 95 % confidence interval for mean of the differences, µd.
