In the end it's just two marks... you can still get band six with a couple little mistakes as long as you knew what you were doing with everything else.
So the question was 'an internet connection has a download speed of 16.8 megabits per second. Approximately how long would it take to download a 120.6 megabyte video file?'
The purpose of the question was to see if you knew the difference between bits and bytes - since they're two different...
Nah it wasn't, they were trying to trip you up with specifics - there's 8 bits in a byte, so a 120.6 megabyte file has 964.8 megabits, so at 16.8 megabits a second it would take 57.43 seconds, which would be C - '57' since you round down.
Similar story with the other one, there's actually 1024MB...