Missing a zero, 100 * 10 = 1000 / 60 = 16.6
The total rep required to get to rank 40 is 100,000, but this also assumes you are making 1000 Rep / game, which is not guaranteed, the rep is based on the amount of coins you receive, and I believe the minimum amount is 500. Which would mean the calculation at the high end is closer too
100,000 / 500 = 200 Games at 10 Minutes = 2000 / 60 = 33 Hours give or take. Assuming you played for 30 minutes a day it would take 66 consecutive days to reach level 40.
If we assume averages,
100,000 Rep / ~750 Rep/match = 133.3~ matches * 12.5 = 1666.25 Minutes / 60 = 27.7 Hours or approximately 55.8~ days if one was to play ~30 minutes per day. In both calculations, assuming everyone is correct and the intended length of the event is indeed 6 weeks or 42 days the player fails to reach the goal playing only 30 minutes a day.
Edit: Very important, you can in fact get almost no rep / match as it turns out, and I’ve seen as low as 7 rep, that would make my 750 rep / match average beyond optimistic, likely meaning the real number for your average player is between 300 - 500. So unless you have persistently stellar performance even accounting for reduced match times in losing early, I imagine you’re looking at the 30-35 hour mark in terms of time invested.