Everything looks good except for the question at the bottom regarding how much water was lost between noon and 1pm. The answer would be to take the volume at 12noon and subtract with the leftover volume at 1pm. That way, you'll find out how much water was lost in that hour, which is 20L.

Question 37) Each small line - represents 2.
So b) 10 + 52 = 62.
c) 52 + 60 + 30 = 142

Question 38) For b) you have to take the remaining volume at 12noon and subtract with the remaining volume at 1pm to see how much water is lost.
For c) the starting time is 10am and the water was emptied at 3pm. So 10am - 11am, 11am - 12noon, 12noon-1pm, 1pm-2pm and 2pm-3pm, would be 5 hours in total.