Sher Khan has three daughters who are all unmarried

Here is a new riddle for you:
Sher Khan has three daughters who are all unmarried. The youngest always lies, the oldest always tells the truth, and the one in the middle either tells the truth or lies. A very rich young man comes to Sher Khan's house and says he wishes to marry one of his daughters. Naturally he wants to marry the oldest or the youngest so he will always know if she is lying or telling the truth. Sher Khan agrees but says he can only ask one of the girls a yes or no question to decide which one he marries. They all look the same age.

What one question does he ask one of the daughters at random to figure out which daughter is the youngest or oldest?