M + D do work in 6 hrs combined
M?
Statement (1) If Michael had left when the job was 1/3 done, it would have taken Donna 8 hours to finish the job by herself.
2/3 of the work was done by D in 8 hrs or 1/3 of the work was done in 4 hrs or full work could have been done in 8+4 = 12 hrs
Together M+D take 6 hrs, so M will take 12 hrs
Sufficient
Statement (2) If Donna had to paint 2 identical sidewalks all by herself, it would have taken her 24 hours to finish.
2 identical in 24 hrs
1 identical in 12 hrs
together with M 6 hrs
M alone = \(\frac{12*6 }{(12-6)}\) = 12 hrs Sufficient
D is the answer
Bunuel wrote:
Working together without taking breaks, Michael and Donna painted the sidewalk in 6 hours. How long would it take Michael to paint the sidewalk by himself?
(1) If Michael had left when the job was 1/3 done, it would have taken Donna 8 hours to finish the job by herself.
(2) If Donna had to paint 2 identical sidewalks all by herself, it would have taken her 24 hours to finish.
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