Originally Posted by Hitch
I would agree with you that to my ear, "1 boy in every 6 is abused" sounds right. I fear, though, that the same reality applies--we're not talking, in this sentence, about ONE boy. We're still talking about 1/6th of all Australian boy(S). And that one boy, singular, is the subject of the sentence, and the "1" is now the modifier, making it clear that it's singular. Thus, we get to "is," rather than "are." The sentence and the meaning would have been better served had the original author written: "16.66% of all Australian boys are molested. That's 1 boy out of every 6," (or "[t]hat's one boy out of every 6 boys," or however s/he wanted to state it).
Look at this in reverse for a second. What if the intent is to indicate a single boy. There is a room with six boys in it and the statement made is: "1 in 6 boys is tall".
This would be correct because your intent is to indicate one boy only. Now the sentence is fairly silly and I can't imagine anyone seriously using "1 in 6" like that. They would possibly write "1 of the 6 boys is tall".
However, and this is where it becomes interesting, what if you actually use a fraction in this case: "1/6th of the boys are tall".
Your intent is to indicate one boy. However, the subject-verb agreement rule states that when you use percentage or fractions as a subject, the verb agrees with the noun that is the object of the prepositional phrase. It's basically an exception to the rule that you never use the object of the prepositional phrase to determine verb agreement. So basically, the above sentence is correct even though the intent is to highlight that only 1 boy is tall.
Now, going back to the original question, I can fully support that the intent of "1 in 6" is "1/6th". To me, it's merely a question of whether we think both of those are identical in every way - including grammatically. I've personally never seen anything written that indicates that "1 in x" should be treated grammatically exactly the same as a fraction or percentage. Therefore, I would apply standard 'remove the prepositional phrase from the equation' logic.
Having written that - this is only to determine what is grammatically correct. What is actually used and accepted, particularly in speech, is usually quite different. While looking into this particular case a little, a linguist chimed in on a similar question with the following:
"One in ten kids is" follows the grammatical rules of standard English. "One in ten kids are" is probably equally likely to be what any given English speaker actually says. So in some sense you are both correct, but the style sheet of a publication is correct to require the singular.
Has anyone found a style sheet that actually specifies "1 in x" should adopt the same rules as a fraction or percentage? Other than forum discussions (like this one), any grammar article I've managed to find that specifically mentions the "1 in x" case states that it should use the singular.
Some of you would be able to get your hands on something much more authoritative than my Google searches.