Multiple choice

Two pipes A & B can fill a tank in 24 min. & 32 min. respectively . If both the pipe are opened simultaneously, after how much time B should be closed so that the tank is full in 18 min?

  1. 8 minutes

  2. 2 minutes

  3. 9 minutes

  4. 3 minutes

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let B be closed after x minutes . Then Part filled by ( A + B ) in x minute + part filled by A in ( 18 - x ) minute = 1 x( 1/24 + 1/32)  + ( 18 - x ) ´ 1/24 = 1 7x/96 + ( 18 - x ) /24 = 1 7x + 4( 18 - x ) = 96 x = 8