For example, we could transfer 900 Mbit for a half of a second and another 100 Mbit for the other half of that second. How much data was transferred during that

For example, we could transfer 900 Mbit for a half of a second and another 100 Mbit for the other half of that second. How much data was transferred during that second? The answer is 1 Gbit per second. The dimensional analysis doesn't work here. He asks for a quantity of data and answers with a transfer rate. Also it shouldn't be surprising that the instantaneous transfer rate at a given time is different than the average transfer rate over a period of time.