A tank is filled in 5 hours by three pipes A, B and C. The pipe C s twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?



[ A ]    35 hr
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[ B ]    30 hr
[ C ]    28 hr
[ D ]    26 hr
[ E ]    None of these
Answer : Option A
Explanation :
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