The total volume of the mixture is $595$ litres. The initial ratio of milk to water is $17:18$.
Let $x$ be the amount of milk (in litres) that needs to be added. The quantity of water remains unchanged.
We can set up the equation based on the final ratio:
$ \frac{\text{New Milk Quantity}}{\text{Water Quantity}} = \frac{3}{2} $
$ \frac{289 + x}{306} = \frac{3}{2} $
To find the value of $x$, we solve the equation:
Therefore, $170$ litres of milk must be added.
Suppose a tap mixes hot water and cold water in a ratio that depends linearly on the proportion of opening. Water out of the tap has temperature 40°C when the tap is half-open, and 30°C when it is three-fourths open. To get water at 50°C, the tap should be_______________.