At different times, two pipes take 5 hours and 8 hours respectively to fill a tank while another third pipe can empty it in 3.2 hours. How long will it take to fill the tank completely when all three pipes are opened simultaneously in a completely empty tank?

Filling pipe A fills 1/5 of tank per hour. Filling pipe B fills 1/8 of tank per hour. Emptying pipe C empties 1/3.2 = 0.3125 of tank per hour. Combined rate = 0.2 + 0.125 - 0.3125 = 0.0125 tank per hour. Time to fill = 1/0.0125 = 80 hours = 3 days 8 hours (since 1 day = 24 hours, 80/24 = 3.33 days). Option B says '3 days 3 hours 36 minute' which is incorrect - the correct answer matches Option D exactly.