You're 27, single, and share a two-bedroom apartment on Columbia Pike with a friend from junior college. Back in July, you met this great guy named Ken at a party in Rehoboth. You've been dating regularly and are almost certain he's stopped seeing his old girlfriend. Ken hasn't exactly talked about marriage or the future, but you are going to the Bahamas together, and he did take you to dinner with his parents when they were in town right before Christmas. Is he really The One? If only there were some test you could take. Some way you could find out For Sure.

Then your roommate brings home the December issue of Cosmopolitan, the one with the cover story, "Exercises to Make You More Responsive to Men (and Help You Find the G-Spot!)." Inside is the monthly Cosmo Quiz, and it reads as if it were written just for You. The quiz, by Junius Adams, is called "How Well Do You Really Know Him?" and it promises to give you "hard data" to help you decide whether life with Ken "will be a bummer or bliss!"

There are 37 multiple- choice questions, and some of them are so intimate theyhave you chewing the end of your pencil. Like this one:

His manner of love-making is . . .

a. happy, playful, spontaneous.

b. thrilling, masterful, a bit scary.

c. tender, intense, loving.

d. not sure yet, can't answer.

Other questions seem so . . . well . . . greedy that they almost make you giggle:

Has he any wealthy relatives from whom he may inherit money or property?

a. Yes.

b. No.

c.Don't know.

810 But there are a few questions that seem right on the mark. They put into words some of your little doubts about Ken:

From what you know of his ambitions, habits, and energy level, he appears . . .

a. dynamic, hard-striving, an achiever.

b. competent, conscientious, ambitious.

c. easygoing and unmotivated.

d.not sure.

810 You begin to get a little nervous as you work your way through the complicated scoring sheet. Ken gets a lot of zeros on the questions about his job prospects, handling of money and his drinking habits. It's even worse when Ken scores only six points for being a "tender" lover. You were sure he was a perfect 10. But to get a 10, he would have to be "thrilling, masterful and a bit scary."

While you're trying to get the courage to add up Ken's score, you take a peek at the part that tells you "What Are Your Prospects Together?" You just know that Ken isn't going to get the 280 points needed to make him "a prime catch--all systems read go." In fact, you're kind of scared that Ken will get less than 170. That, according to Cosmo, means, "Prognosis gloomy. If you marry this man it will have to be for love alone, because he doesn't have much else to offer."

It's not as bad as you feared. At the end of the quiz, Ken musters 188 points--the lower end of the middle range. Cosmo gives it to you straight: "Socially, sexually, or economically . . . this man has limitations or deficiencies that are certain to cause difficulties." There are also a few words of encouragement ("You can get along if you work at it"), but by the time you read them you're beginning to see Ken in a new light.

Your mind is full of questions. Should I cancel the trip to the Bahamas? Drop Ken before his "limitations or deficiencies" cause too much pain? Can I really believe this stupid Cosmo quiz? Is it scientific? Or just another way of selling magazines?

Junius Adams is to the Cosmo quiz what Rorschach is to inkblots. First as articles editor of Cosmopolitan and later as a free-lancer, Adams estimates that in the last 15 years he has written, rewritten and edited more than 100 of these monthly self-help quizzes. Barbara Creaturo, the Cosmopolitan editor who is currently in charge of the feature, describes Adams as "our quiz maven. He does them more skillfully than any other Cosmo writer."

Adams, a New York writer in his late 50s whose hair and beard are more white than gray, seems almost resentful as he muses on his success in mastering the Cosmo quiz. "For me, it's a little annoying," he said. "I write essays and short stories, but when people contact me, it's always because of those damn quizzes." Adams, now a contributing editor to Cosmopolitan, says he's having trouble selling his latest book project --a profile of a New York psychic healer.

The monthly Cosmo quiz is one of the hallmarks of the reign of editor Helen Gurley Brown. But it was Adams, as articles editor, who decided that the quizzes didn't need to be written by experts. "We started out using psychologists to write the quizzes," Adams recalled. "But when you get stuff from a supposed expert, you end up having to rewrite it anyway. So in my selfishness as an editor, I decided that I'd rather deal with writers who can write."

These days, Cosmo doesn't use psychologists even to check the quizzes for accuracy before they appear in the magazine. "We take them ourselves in the office to see if they work," explained Creaturo. "It's not exactly scientific, but we're not a scientific journal. Anyway, they probably work about as well as a real psychological test."

Like everything else at Cosmo, there is a formula to writing the quizzes. According to Adams, the "basic format" is usually "How (Something) Are You?" The "Something" could be anything from "Generous" to "Promiscuous" to "Sexually Threatening to Men." But the important thing, Adams said, is that "the results should be flattering to everyone."

He cited as a typical example a quiz on sexual responsiveness. "The range of answers will go from totally roundheeled to totally frigid," Adams said. "But, of course, you don't put it like that." In fact, one Cosmo quiz (not written by Adams) used the phrase "free spirit who lets very little stands in the way of pleasure pursuits" to describe a woman who would hop in the back seat with an amorous taxicab driver. As a euphemism for frigid, Adams offered: "You're totally discriminating and someone will have to show you their true worth before you'll open up."

Adams was hazy on how he had put together the "How Well Do You Really Know Him?" quiz, which was completed 18 months before it appeared on newsstands last December. The author did recall that he had written the quiz off the top of his head, but added that it was based on research he had done for earlier Cosmo quizzes and articles on marital compatibility. "It's a valid questionnaire," he insisted. "If you get a very low score, then the man's sort of a loser. Maybe there are wonderful losers out there."

In her introduction to The Cosmo Quiz Book, a 1980 collection, Helen Gurley Brown wrote, "I'll bet you come away from them with a more secure idea of who you are and of how you can get the most happiness and good out of life." That sounds like about what you could reasonably expect from five years of psychotherapy.

Adams, for one, is not nearly as messianic about his work: "I don't believe that the people who take these quizzes actually find out about things. Answering questions is the next best thing to getting someone to pay attention to you, the next best thing to going to a shrink." His editor, Barbara Creaturo, adds, "They're for fun. They're not definitive. People don't make life decisions based on a Cosmo quiz."

That's good to know. Especially if you were thinking of dumping Ken and canceling that vacation trip to the Bahamas.