Beginning at noon yesterday, water was removed from a partially filled water tank at a constant rate of 300 liters per hour. When there were 600 liters of water left in the tank, no more water was removed from the tank. Were there more than 1,000 liters of water in the tank at noon yesterday?Observe that the question essentially asks whether more than 400 liters of water was removed or whether the water removal lasted more than 400/300 = 4/3 hours (80 minutes).
(1) There were 600 liters of water in the tank at 2:00 yesterday afternoon.
It's unclear when the removal stopped. It could have been any time between noon and 2:00 pm. If it stopped right at 2:00 PM, then the water was removed for two hours, totaling 2*300 = 600 liters. In this case, the initial amount in the tank would be 600 + 600 = 1,200 liters. However, if the removal stopped earlier, say at 1:00 pm, only 300 liters would have been removed, making the initial amount 600 + 300 = 900 liters. Hence, this statement alone is not sufficient.
(2) There were more than 650 liters of water in the tank at 1:00 yesterday afternoon.
Since 300 liters were removed between noon and 1:00 pm, the initial amount was more than 650 + 300 = 950 liters. But this doesn't specify how much more than 950 liters, so it's unclear if it exceeded 1,000 liters. This statement alone is also not sufficient.
(1)+(2) We still don't know the exact time when the water removal stopped. Therefore, we still cannot definitively say if there were more than 1,000 liters in the tank at noon. For example, consider the following two cases:
- Case 1: If the water removal lasted for 2 hours (until 2:00 pm), then the initial amount in the tank was 1,200 liters (at 1:00 pm - 900 liters, which is more than 650 liters).
- Case 2: If the water removal lasted for 4/3 hours (80 minutes) (until 1:20 pm), then the initial amount in the tank was 600 + 4/3*300 = 1,000 liters (at 1:00 pm - 700 liters, which is more than 650 liters)
Not sufficient.
Answer: E.