What are the odds?

'The odds' are what is set by bookmakers. In real life, all you can say with certainty is that it is very unlikely. It is possible to predict certain events with some accuracy (like the WEATHER ;) ), but not really the movement of people.

He's asking for a probability, that's all. You've said nothing there but patronising nonsense. It is possible to come up with a reasonable probability based on simple assumptions about the movement of people.

For example the probability of chancing upon someone in a city is higher than not, as is the case for public transport.