A) 6h
B) \[6\frac{2}{3}h\]
C) 7h
D) \[7\frac{1}{2}h\]
Correct Answer: C
Solution :
A take 12 h to fill 1 tank \[\therefore \] A takes 1 h to fill \[\frac{1}{12}\] tank B takes 15 h to fill 1 tank B takes 1 h to fill \[\frac{1}{15}\] tank C takes 20 h to fill 1 tank C takes 1 h to fill \[\frac{1}{20}\] tank \[\frac{\frac{1}{12}+\frac{1}{15}}{1\,h}+\frac{\frac{1}{20}+\frac{1}{12}}{2nd\,h}+\frac{\frac{1}{15}+\frac{1}{12}}{3rd\,h}\] \[+\frac{\frac{1}{20}+\frac{1}{12}}{4th\,h}+\frac{\frac{1}{15}+\frac{1}{12}}{5th\,h}+\frac{\frac{1}{20}+\frac{1}{12}}{6th\,h}+\frac{\frac{1}{15}+\frac{1}{12}}{7th\,h}\] \[=\frac{5+4+3+5+4+5+3+5+4+5+3+5+4+5}{60}\]\[=\frac{60}{60}=1=7\,\,h\]You need to login to perform this action.
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