This distance-time graph shows part of the journey of a boat. What was the speed of the boat between 40 and 60 seconds after starting? Give your answer in metres per second $(\mathrm{m} / \mathrm{s})$ and give any decimal answers to 1 d.p.

Step 1 ：From the graph, we can see that at 40 seconds, the boat has traveled 200 meters, and at 60 seconds, the boat has traveled 300 meters.

Step 2 ：So, the distance the boat traveled between 40 and 60 seconds is \(300 - 200 = 100\) meters.

Step 3 ：The time taken for this part of the journey is \(60 - 40 = 20\) seconds.

Step 4 ：The speed of the boat during this time is the distance traveled divided by the time taken, which is \(\frac{100}{20} = 5\) meters per second.

Step 5 ：So, the speed of the boat between 40 and 60 seconds after starting is \(\boxed{5}\) meters per second.