Joe was both fifth highest and fifth lowest in a race How many people in the race?

There are 9 people in the race.

Think about it this way - for him to be 5th highest, there must be 4 people above him (1st place, 2nd, 3rd and 4th).

For him to be 5th lowest, there are also 4 people below him.

So 4 above plus 4 below plus him = 9 participants