Multiple choice

Pipes P and Q can fill a tank in 10 and 12 minutes respectively and C can empty it in 6 minutes. If all the three are opened at 7 a.m., at what time will four time of the tank will be filled? P और Q नल एक टंकी को क्रमशः 10 और 12 मिनट में पूरा भर सकते हैं तथा उसी टंकी को एक अन्य नल C, 6 मिनट में खाली कर सकता है। यदि तीनों नल एक साथ 7 बजे प्रातः चालू कर दिये जायें, तो टंकी का चार गुनी क्षमता वाली टंकी कितने समय तक भर जायेगी?

  1. 10 a.m.

  2. 10 p.m.

  3. 11 p.m.

  4. 11 a.m.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pipe P fills at 1/10 tank per minute, Q fills at 1/12 tank per minute, C empties at 1/6 tank per minute. Net fill rate = 1/10 + 1/12 - 1/6 = (6 + 5 - 10)/60 = 1/60 tank per minute. At this rate, filling one tank takes 60 minutes = 1 hour. Starting at 7 a.m., one tank fills by 8 a.m. For four tanks: 4 × 60 = 240 minutes = 4 hours. 7 a.m. + 4 hours = 11 a.m.

Keep practicing — related questions