Two pipes A and B can fill an empty tank in 10 hours and 16 hours respectively. They are opened alternately for 1 hour each, opening pipe A first. In how many hours, will the empty tank be filled?
Answer & explanation
Correct answer: option 4
A+ = 10 hrs, B+ = 16 hrs,
⇒ They are opened alternatively started with A
1st hour = 8 units,
2nd hour = 5 units,
Every 2 hours, 13 units of tank is filled,
So, in 12 hours, 78 units of tank is filled,
Therefore, in $12\frac{1}{4}$ hours, full 80 units of tank is filled.