A) 45
B) 48
C) 54
D) 57
E) 63
Correct Answer: C
Solution :
A is 80% more efficient then B. \[\therefore \]Ratio of time taken by A and B= 100 : 180=5 : 9 \[\therefore \,\frac{1}{5x}+\frac{1}{9x}=\frac{1}{19\frac{2}{7}}\] \[\Rightarrow \,\frac{9+5}{45x}=\frac{7}{135}\] \[\Rightarrow \,\frac{14}{45x}=\frac{7}{135}\] \[=\frac{2}{x}=\frac{1}{3}\Rightarrow x=6\] \[\therefore \] Time taken by B \[=9x=9\times 6\] =54 daysYou need to login to perform this action.
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