I have a line in a file like this:

`NORMFLY 306130.10 199963.09 5000.00 300.00`

I want to use C# regex to replace the third decimal in the series with a random decimal. The value of the 3rd decimal may vary with different lines. `^NORMFLY \d+(\.\d{1,2})? \d+(\.\d{1,2})? \d+(\.\d{1,2})?` will match up to the end of the 3rd decimal, but I can't figure out how to replace the match with something different.

So for example, change:

`NORMFLY 306130.10 199963.09 **5000.00** 300.00`

to

`NORMFLY 306130.10 199963.09 **7690.56** 300.00`