Question

Jill takes 2 hours to paint a room, Jim takes 3 hours to paint a room. How long (in minutes) will it take both of them to paint a room

Answer 1

72 minutes

Explanation:

The sum of the rates of work in rooms per hour is ...

Jill's rate + Jim's rate

= (1/2 room/hour) +(1/3 room/hour) = (3/6 +2/6 room/hour) = 5/6 room/hour

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Then the combined rate in hours per room is ...

1/(5/6 room/hour) = 6/5 hours/room = (6/5 hours/room)(60 minutes/hour)

= 72 minutes per room

Jill and Jim can paint the room in 72 minutes when they work together.