Working out average scan time of 100 ballots per minute. Part 3

When Things Go Wrong.
START 11:03:00 END 11:52:37 = 50 min
Purple shirt Replaced bold guy with white shirt, he left with the rest of the people. Training on the fly?
It took 50 min to scan 9 batches of which 4 were accepted.
400 Ballots ÷ 15 MIN = 26 Ballots P/M (35 min lost)
Actual Ballots p/m counted, 400 Ballots ÷ 50 min = 8 Ballots P/M