A father can do job as fast as 2 sons working together. If one son does the job in 3 hours and the other in 6 hours, the number of hours taken by the father, to do the job alone is
Time taken by the two sons in doing the job = 3 hours and 6 hours
=> Father's efficiency = $$\frac{1}{3}+\frac{1}{6}$$
= $$\frac{2+1}{6}=\frac{3}{6}=\frac{1}{2}$$
$$\therefore$$ Time taken by father = 2 hours
=> Ans - (B)
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