# Test a conjecture of your own

On paper, choose a positive two-part ratio and compare totals 6, 12 and 18 in one named length unit. Predict what will remain the same before calculating. Test your prediction. Then change just one ratio component and describe what changed. If any selected total creates fractional counts, switch to a length model or explain why whole counts cannot meet it.

**Check:** a valid response uses the same positive scale factor on both components, labels units and distinguishes a part:part ratio from a fraction of the whole. For the optional example 1:2 in metres, totals 6, 12, 18 give (2, 4), (4, 8), (6, 12). The proportion of the first part is always 1/3. Your own different ratio may give different answers; the reasoning is the check.