A liquid medicine is prepared according to the ratio of medicine powder and water 1:2500. Now 15 grams of medicinal powder is prepared into such a liquid medicine, how many kilograms of water need to be added?
一种药水是按药粉和水的比1：2500配制成的．现在用药粉15克配制成这样的药水，需要加水多少千克？
<gadget id="calculator">1 / 2_500</gadget>
<output>1/2_500 = around 0.0004</output>

<gadget id="calculator">15 / (1/2_500) / 1_000</gadget>
<output>75/2 = around 37.5</output>

<result>75/2 = around 37.5</result>