90 minutes
First, we see that at 0 minutes, the container is completely full at 900ml. If you look on the graph, you can see that the container is at 800ml after 10 minutes. This is key because it tells us that the container leaks 100ml every 10 minutes. We can then figure up that 900, when losing 100ml every 10 minutes, will eventually run dry after 90 minutes. You can set up a proportion to check your work, which would look like this: 10 over 100 is equal to x over 900.
