Set up a ratio problem. If the ratio cannot be reduced to an equivalent ratio in terms of small integers, then express it as a ratio of decimal equivalents with the smallest term set at 1. Maintain three figure accuracy.

The instructions for preparing the fuel mix for a two-cycle engine are to add 250 millilitres of oil to 5 millilitres of gasoline. What is the ratio (by volumes) of gasoline to oil in the fuel mix?