# Two water taps together can fill a tank in hours. The tap of larger diameter takes 10 hours less than the smaller one to fill the tank separately. Find the time in which each tap can separately fill the tank.

Let the time taken by the smaller pipe to fill the tank be x hr.

Time taken by the larger pipe = (x − 10) hr

Part of the tank filled by a smaller pipe in 1 hour = Part of the tank filled by the larger pipe in 1 hour = It is given that the tank can be filled in hours by both the pipes together.
So 75/8 hours, multiplied by the sum of parts filled with both pipes in one hour equal to complete work i.e 1. ⇒ ⇒ ⇒ ⇒ 75(2x - 10) = 8x2 – 80x

⇒ 150x – 750 = 8x2 – 80x

⇒ 8x2 – 230x + 750 = 0

Now for factorizing the above quadratic equation, two numbers are to be found such that their product is equal to 750 x 8 and their sum is equal to 230

⇒ 8x2 – 200x – 30x +750 = 0

⇒ 8x(x – 25) – 30(x – 25) = 0
⇒ (x – 25 )(8x – 30) = 0

⇒ x = 25, Time taken by the smaller pipe cannot be = 3.75 hours.

As in this case, the time taken by the larger pipe will be negative, which is logically not possible.

Therefore, time taken individually by the smaller pipe and the larger pipe will be 25 and 25 − 10 =15 hours respectively.

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