Katie had to run to catch the subway, got off two stops later, and then walked to school. Which of the following speed-time graphs would best represent her journey? So when Katie makes her journey, because she runs to catch a subway, then stops once, and then stops again, and then walks to school, in total, she'll stop four times. In these graphs, we can see that A stops five times, B stops four times, C stops three times, D stops four times, and E stops five times. Therefore, we can narrow our answers down to B or D. We're also told that she first runs, meaning that her speed at the beginning should be faster than her speed at the end, but not faster than the subway speed, because the subway is presumably faster than her running speed. Also, the subway is going on the tracks, and it should be going at a pretty constant speed, so the two middle bumps should be at the same height. Therefore, since we can only have B or D, D is clearly the correct answer, because the running speed is greater than the walking speed, and the running speed is also slower than the two subway speeds. D is our correct answer.

speed-time graph

Katie's journey

subway speed

running speed

walking speed