Multiple choice

Two pipes A and B can fill a cistern in 16 min and 24 min respectively. Both are opened together at the end of 6 min, A is turned off. in how much time will the cistern be full ?

  1. 22 min

  2. 19 min

  3. 17 min

  4. 15 min

  5. N/A
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Part filled by ( A + B) in 6 min = ( 1/16 + 1/24 ) x 6 = 5/ 48 x 6 =5/8 Remaining part = ( 1 - 5/8 ) = 3/8 1/24 part is filled by B in i min. 3/8 part is filled by B in (24 x 3/8) =9 min Therefore total time taken to fill the cistern = (6 + 9) =15 min

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