There's quite a few of those signs around the country now.

On the way up here to Mackay there is a sign with a question re the native flower of Qld......some distance down the road is the answer. 

Unfortunately they did not continue on with the idea, though there is a repeat of the same sign and question further along the road.  Must have both been in the same shire.

Pity, I enjoyed the trivia.....probably because I knew the answer.  LOL