Peter painted 1/3 of a room while Joe painted 2/5 of the same room. It then took Peter 1 hour, 40 minutes to finish painting the remainder of the room by himself. In how many hours could Peter have painted the entire room by himself? Express answer as a mixed number.

2 answers

The fraction of the room still to be painted after the two sessions
= 1 - 1/3 - 2/5 = 4/15

so 4/15 or room took 1 hr 40 min or 5/3 hour

so 1 room took (5/3)(15/4) hours or 6.25 hours
or 6 hours and 15 minutes.
mixed number: 6 1/4 hours.
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