A) 10 min 20 s
B) 11 min 45 s
C) 12 min 30 s
D) 14 min 40 s
Correct Answer: D
Solution :
Part filled by both in 4 min \[=4\times \left( \frac{1}{15}+\frac{1}{20} \right)\] |
\[=\left( 4\times \frac{7}{60} \right)=\frac{7}{15}\] |
Pact unfilled \[=\left( 1-\frac{7}{15} \right)=\frac{8}{15}\] |
\[\frac{1}{20}\]part is filled by B in 1 min |
\[\frac{8}{15}\]part is filled by B in \[\left( 20\times \frac{8}{15} \right)\]min |
\[=\frac{32}{3}\min =10\min 40\,\,s\] |
Total time taken = (4 min +10 min 40 s) = 14 min 40 s |
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