A running coach wanted to see whether runners ran faster after eating spaghetti the night before. A group of six runners was randomly chosen for this study. Each ran a 5 kilometer race after having a normal dinner the night before, and then a week later, reran the same race after having a spaghetti dinner the night before. The times for their races are shown in the table below. What test value should be used in a t test for these dependent samples?
Run 1 Run 2 Run 3 Run 4 Run 5 Run 6
Regular Dinner 1000 s 985 s 1009 s 970 s 1016 s 996 s
Spaghetti Dinner 992 s 979 s 1005 s 968 s 1016 s 998 s
a) 3.80
b) 0.80
c) 1.55
d) 1.96