The graph shows the velocity of a train.
a) Use four strips of equal width to estimate the distance the train travelled in the first 20 seconds.
b) Is your answer to part a) an underestimate or overestimate?
![The graph shows the velocity of a train a Use four strips of equal width to estimate the distance the train travelled in the first 20 seconds b Is your answer t class=](https://us-static.z-dn.net/files/d24/25825c33c6f724791dcf80175c3db756.png)