You can see on the graph that the charged percentage of capacity changes from 40 to 50 in 5 minutes. Then the increase in 6 minutes will be slightly more than 10 percent.
The linear rate is (10%)/(5 min) = 2%/min, so in 6 minutes it will be
(2%/min)×(6 min) = 12%
This calculation is consistent with our observation from the graph.
Every 6 minutes, 12 percent is added to the capacity.
