1. Diego runs a 10-kilometer race and keeps track of his speed. What was Diego's speed at the 5-kilometer mark in the race?
2. According to the graph, where was Diego when he was going the slowest during the race?
3. Diego runs a 10-kilometer race and keeps track of his speed.

Describe what happened to Diego's speed in the second half of the race (from 5 km to 10 km).