Question 973048
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Painter: 1 room/5 hours=1/5 room/hr
Assistant: 1 room/8 hours=1/8 room/hr
In 1/2 hour, the painter paints 1/10 of the room and the assistant paints 1/16 of the room. 1/10+1/16=8/80+5/80=13/80. 13/80 has been painted leaving 1-13/80=67/80 to paint. The assistant paints 1/8 room per hour (10/80 room per hour) so to paint 67/80 room takes (67/80)/(10/80)=6.7 hours
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ANSWER: It takes the assistant 6.7 hours to finish the room.