In the sentence "one in ten people hate..." which is the correct way to refer to 1/10:
"One in ten" or "One-in-ten"
I'm not too sure if the hyphens are entirely necessary here. I have however seen news articles that use hyphens with this phrase and some that don't, which leaves me unsure whether the hyphens are needed or not.
"One in ten people hate ..." is correct. But if you use the phrase as an adjective ("A one-in-ten chance") hyphens are a good idea.
Using hyphenation is typically a question of style preference, and some well know style guides can be checked to determine what is appropriate. However, a few guidelines are worth knowing.
The guidelines below come from an answer to another question about a specific use of hyphenation. But the guidelines are very general.
Let's start with the British Guardian and Observer Style Guide, where I'll emphasis some relevant points:
(1)
Our style is to use one word wherever possible. Hyphens tend to clutter up text (particularly when the computer breaks already hyphenated words at the end of lines). This is a widespread trend in the language: "The transition from space to hyphen to close juxtaposition reflects the progressive institutionalisation of the compound," as Rodney Huddleston puts it, in his inimitable pithy style, in his Introduction to the Grammar of English.
(2)
There is no need to use hyphens with most compound adjectives, where the meaning is clear and unambiguous without: civil rights movement, financial services sector, work inspection powers, etc.
(3)
Also use hyphens where not using one would be ambiguous, eg to distinguish "black-cab drivers come under attack" from "black cab-drivers come under attack". A missing hyphen in a review of Chekhov's Three Sisters led us to refer to "the servant abusing Natasha", rather than "the servant-abusing Natasha".
This implies that you should not use hyphens when there would be no ambiguity without them.
(4)
Prefixes such as macro, mega, micro, mini, multi, over, super and under rarely need hyphens
I could stop and summarize there, but let's look at an American style guide, the Chicago Manual of Style (drop down to #4 in that document):
(5)
Compounds formed with prefixes are normally closed, whether they are nouns, verbs, adjectives, or adverbs...(3) to separate two i’s, two a’s, and other combinations of letters or syllables that might cause misreading, such as anti-intellectual, extra-alkaline, pro-life;
You may also want to take a look at other style guides, like The Chicago Manual of Style. Typically, these well known style guides will reinforce what is stated above.
To summarize in the context of your example, no hyphens should be necessary, because there is no ambiguity in meaning created without them. This is true even when used as a phrasal adjective.
However, the Grammarist (grammarist.com) takes a different viewpoint on this subject when it comes to phrasal adjectives:
When a phrasal adjective precedes a noun, it usually takes a hyphen or, for phrases of three or more words, hyphens. This makes things easier for your reader and helps prevent miscues.
This is followed by exceptions to the rule:
The same phrases are unhyphenated when they come after what they modify.
and
We make exceptions for phrasal adjectives beginning with -ly adverbs. These are conventionally unhyphenated.
These rules tend rank readability (avoiding "miscues") above concern for the clutter that using hyphens can create, and has merit. But the style guide quoted above says that if there is no readability problem (no miscues, no ambiguity), the the hyphens can be omitted.
