A and B can do a job together in 7 days. A is $$1\frac{3}{4}$$ times as efficient as B. The same job can be done by A alone in :
A. $$9\frac{1}{3}$$ days
B. 11 days
C. $$12\frac{1}{4}$$ days
D. $$16\frac{1}{3}$$ days
Answer: Option B
Solution(By Examveda Team)
$$\eqalign{ & \left( {{\text{A's}}\,{\text{1}}\,{\text{day's}}\,{\text{work}}} \right){\text{:}}\left( {{\text{B's}}\,{\text{1}}\,{\text{day's}}\,{\text{work}}} \right) \cr & = \frac{7}{4}:1 = 7:4 \cr & {\text{Let}}\,{\text{A's}}\,{\text{and}}\,{\text{B's}}\,{\text{1}}\,{\text{day's}}\,{\text{work}}\,{\text{be}} \cr & 7x\,{\text{and}}\,4x\,{\text{respectively}} \cr & {\text{Then}},\,7x + 4x = \frac{1}{7} \cr & \Rightarrow 11x = \frac{1}{7} \cr & \Rightarrow x = \frac{1}{{77}} \cr & \therefore {\text{A's}}\,{\text{1}}\,{\text{day's}}\,{\text{work}} \cr & = {\frac{1}{{77}} \times {\text{7}}} = \frac{1}{{11}} \cr} $$So, A will do the work in 11 days
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