Question 1196928
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The response from the other tutor shows a typical formal algebraic solution.<br>
Here are a couple of less formal methods for solving this kind of problem, if formal algebra is not required.<br>
(Note, however, that even if a formal algebraic solution is required, you can get good mental exercise (and good problem-solving experience) by solving the problem using logical reasoning.)<br>
One common alternative to the solution method shown by the other tutor is to consider the least common multiple of the two given times, which is 24 hours.<br>
In 24 hours the one pump could fill the tank 24/8 = 3 times; in 24 hours the two pumps together could fill the tank 24/3 = 8 times.<br>
That means the other pump could fill the tank 8-3 = 5 times in 24 hours; and that means it could fill the one tank in 24/5 hours, or 4 4/5 hours, or 4 hours 48 minutes.<br>
And another solution method using logical reasoning is that, because the one pump can fill the tank alone in 8 hours and the two pumps together can fill it in 3 hours, in those 3 hours the one pump can fill 3/8 of the tank.<br>
That means in those 3 hours the other pump can fill 5/8 of the tank; and that means the number of hours required for the other pump alone to fill the tank is 3(8/5) = 24/5 hours.<br>