Multiple choice

Pipe A can fill a tank in 45 hr, pipe B is 50% more efficient than A and pipe C can fill the same tank in 7.5 hr less than B. A and B opened together for X hr and closed after that and pipe C fill remaining tank in (X + 9) hr, if the ratio between tank filled by (A+

  1. 3 hr

  2. 4 hr

  3. 6 hr

  4. 8 hr

  5. 7 hr
Reveal answer Fill a bubble to check yourself
C Correct answer
AI explanation

Pipe A fills the tank at a rate of 1 divided by 45 per hour, and since pipe B is 50 percent more efficient, its rate is 1 divided by 30 per hour. Pipe C takes 7.5 hours less than B, meaning its rate is 1 divided by 22.5 per hour, or 2 divided by 45 per hour. Pipes A and B work together for X hours to fill 1 divided by 18 of the tank per hour, and pipe C works for X plus 9 hours; applying the given ratio of 1 to 2 for the work done, we find the total work equation is X divided by 18 equals 2 multiplied by the quantity of 2 divided by 45 multiplied by the quantity of X plus 9. Solving 5X equals 4X plus 36 gives X equals 6 hours.

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