A) 60
B) 30
C) 20
D) 15
Correct Answer: C
Solution :
[A + B]?s 1 day's work \[=\frac{1}{12}\] ? (i) [B + C]?s 1 day's work \[=\frac{1}{15}\] ? (ii) \[\therefore \]Difference between A and C?s 1 day's work \[=\frac{1}{12}-\frac{1}{15}=\frac{5-4}{60}=\frac{1}{60}\] If A alone completes the work in \[x\] days, C will do the same in \[2x\] days. \[\therefore \] \[\frac{1}{x}-\frac{1}{2x}=\frac{1}{60}\] \[\Rightarrow \] \[\frac{2-1}{2x}=\frac{1}{60}\] \[\Rightarrow \] \[\frac{1}{2x}=\frac{1}{60}\] \[\Rightarrow \] \[x=30\] \[\therefore \]B's 1 day?s work \[=\frac{1}{12}-\frac{1}{30}\] [From equation (1)] \[=\frac{5-2}{60}=\frac{3}{60}=\frac{1}{20}\] Hence, B alone will complete the work in 20 days.You need to login to perform this action.
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