Famous Pickup Line Experiment

Here's a famous experiment that was actually conducted:

An attractive member of the opposite sex goes up to people, and asks them one of three questions: 

I find you very attractive, would you like to...

1) Go on a date with me? 

2) Go back to my apartment?

3) Have sex with me? 

50% of women who were asked #1 answered yes. 

6% of women who were asked #2 answered yes. 

0% of women who were asked #3 answered yes. 

But... 

50% of men who were asked #1 answered yes. 

67% of men who were asked #2 answered yes.

75% of men who were asked #3 answered yes. 

That's some very asymetrical results between the differences of the sexes.  Not only are there radically different answer percentages, but men are more likely to have sex than go on a date.  Whereas women would rather go on a date than have sex.

Why are men less likely to go on a date than have sex, and women are answering completely differently?   Not just in different numbers, but with completely different values, apparently?