How does the speed of a runner vary over the course of a marathon (a distance of 42.195 km)? consider determining both the time to run the first 5 km and the time to run between the 35-km and 40-km points, and then subtracting the former time from the latter time. a positive value of this difference corresponds to a runner slowing down toward the end of the race. the accompanying histogram is based on times of runners who participated in several different japanese marathons.†