A water tank is two-fifth full. Pipe A can fil a tank is filled in 10 minutes and pipe B can empty it in 6 minutes. If both the pipe are open, how long will it take to empty or fill the tank completely?

Question

নিচের অপশন গুলা দেখুন

• 6 min. to empty
• 6 min. to fill
• 6 min. to fill
• 9 min. to empty

Answer 1

সঠিক উত্তর হচ্ছে: 6 min. to empty

ব্যাখ্যা: Since pipe B is faster, the tank will be emptied.
Work done by pipe A in 1 min = 1/10
Work done by pipe B in 1 min = ⅙
Total work when A and B are opened = ⅙ – 1/10
= 4/60
= 1/15
Part emptied in by A and B 1 min = 1/15
Time taken to empty 2/5 of the tank = (⅖)/(1/15)
= 6 min