OG math question

I’m trying to figure out the OG of my latest brew.

Sinistral Warrior IPA, Partial Mash
subbed 4# 2-row for the 3.15 LME
6# LME
and I added 1/2 # DME just in case.

target OG (without my added DME) 1.065

here’s what I got:

OG from undiluted cooled wort, 4.5 gal = 1.072
I added 1 gallon water for 5.5 gallons total.

how do I figure my OG? for 5.5 gallons, right?
what is the gravity of water?

thanks for any tips!

Simply multiply the gravity by the ratio of the volumes → 72*4.5/5.5 = 59 or 1.059

good thing I added that DME.

now, the target OG from the NB recipe sheet, is that for 5 gallons?

if so, I could figure for 5 gallons as well, to compare?

???

ok, I just realized that I have closer to 5 gallons with about 1/2 gallon trub in bottom of carboy.
so then the OG would be closer to 1.065.

my whirlpooling didn’t work so well this time, lots of hop!

I may go back to the hop bags.