A tank was filled with 190 ℓ of water at 16 00. Water flowed out of the tank from 16 00 to 20 00. The line graph shows the amount of water in the tank from 16 00 to 20 00. Which one-hour period shows the most increase in the amount of water in the tank? Give your answer in this format. (Eg 12 00 to 13 00)


To find the most increase in a line graph, look for a decreasing slope that is the steepest. This indicates that the most decrease in the amount of water in the tank.

To show:

Between 16 00 and 17 00:
Volume of water that flowed out
= 190 - 140
= 50 ℓ

Between 17 00 and 18 00:
Volume of water that flowed out
= 140 - 135
= 5 ℓ

Between 18 00 and 19 00:
Volume of water that flowed out
= 135 - 110
= 25 ℓ

Between 19 00 and 20 00:
Volume of water that flowed out
= 110 - 90
= 20 ℓ

One-hour period that shows the most decrease in the volume of water = 16 00 to 17 00 

Answer(s): 16 00 to 17 00