There are an odd number of numbers.

5200 2800 1150 900 850 850 750

The median of a highway is in the middle of the highway.
The median of a set of numbers is the one in the middle of the set of numbers,
when they are arranged from largest to smallest or smallest to largest.

Those are arranged largest to smallest, so the middle one is 900.

So the median is 900.

----------------------------------------------------------------------

When there are an even number of numbers, you don't have a middle one, 
but you have a middle two, and so you average them.

If you have  109  97  67  45  26  15, and want to find the median,
You take the middle two, which are 67 and 45, so you average them:
 = 56

Edwin