Multiple choice

If two pipes function simultaneously, a tank is filled in 12 hours. One pipe fills the tank 10 hours faster than the other. How many hours does the faster pipe alone take to fill the tank?

  1. 20

  2. 22

  3. 25

  4. 30
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let slower pipe take x hours, so faster takes (x-10) hours. Together: 1/x + 1/(x-10) = 1/12 (tank per hour). Multiplying: 12(x-10) + 12x = x(x-10). This gives 12x-120+12x = x^2-10x, so x^2-34x+120 = 0. (x-30)(x-4) = 0. x=30 (since x>10). Faster pipe = 30-10 = 20 hours.

Keep practicing — related questions