One in four NOT plural
The context that one (a singular entity) out of four (a group of four, a plural) is obese. One of them is. Not one of them are. It's almost frighteningly simple and you aren't an actual retard so I know you're just winding me up and I'm not falling for it (any more).
( Monty Boyce, My cheese game is strong, Thu 18 Apr 2013, 9:34, 2 replies, latest was 12 years ago)

Yes, but they didn't just survey 4 kids and find one fat one, did they?

(localboy purveyor of pisspoor puns, Thu 18 Apr 2013, 9:37, Reply)

DON'T YOU FUCKING START,
They surveyed all of them and if you break them down into groups of four, out of that group of four one of them IS fat.

Now fuck off.
( Monty Boyce, My cheese game is strong, Thu 18 Apr 2013, 9:40, Reply)

I doubt they surveyed all of them.
More likely a sample group, then the figures scaled up.
( tangledupinblue hairy badge with moving eyes, Thu 18 Apr 2013, 9:44, Reply)

IF The four represents more than four.
THEN the one represents more than one.
THEREFORE plural
(PsychoChomp, Thu 18 Apr 2013, 9:40, Reply)

EXACTLY
It's a statistical description, not a quantity.

Oh. ...quantities, I see the difficulty now.
(localboy purveyor of pisspoor puns, Thu 18 Apr 2013, 9:43, Reply)