Problema Solution
a water tank can be filled in 8 minutes and emptied in 9 minutes. If the drain is left open when being filled how long will it take to fill
Answer provided by our tutors
Let t = time in minutes empty the tank with both valves open
let an empty tank = 1
:
- = 1
multiply by 72 to clear the denominators, results:
9t - 8t = 72
t = 72 minutes