Simplify the ratio by dividing both numbers by their HCF.<br><br>
&bull; Oats : Water = \(2 : 6\)<br>
&bull; HCF of 2 and 6 is 2.<br>
&bull; \(2 \div 2 = 1\), \(6 \div 2 = 3\)<br>
&bull; Ratio = \(1 : 3\)<br><br>
Final Answer: 1 : 3