「worth, worthy, worthwhile」の違いは何？

"Why have you put another picture of a banana here, Nick?" you may be asking.

I know someone who hates bananas. I asked her if she had ever eaten a Sembikiya banana. I had never eaten one, but theoretically, they should have some of the best bananas in Japan.

• theoretically 理論上｛りろんじょ う｝は、名目上｛めいもく じょう｝は、理論的｛りろんてき｝に言えば (definition from Eijiro on the Web)

I asked her if she would be willing to try a Sembikiya banana. She said yes, so today we ate Sembikiya bananas as an experiment.

Bravely, she ate one quarter of a banana without making too many strange faces. She didn't want any more, though.

Of course it tasted pretty good, since it's from Sembikiya. I prefer green bananas, and these were slightly green. I was happy about that.

However, I didn't think it was worth it. <- "worth" is a preposition! I learned something!

• It wasn't quite worth it, was it? (definition from Eijiro on the Web)
  そんな価値はなかったね？

They aren't worth 210円 each, though. <- see? "210円" is a noun, and "worth" is a preposition...

Doing the experiment was worthwhile, though. <- "worthwhile" is an adjective

• worthwhile 【形】やりがいのある、値打ちのある、価値｛かち｝のある、無駄｛むだ｝ではない (definition from Eijiro on the Web)

The experiment was worthy to try. <- Maybe this is ok, but... I never say "worthy"...

• worthy ～に値する、～するに足りる (definition from Eijiro on the Web)

The experiment was worth trying. <- Ah... this is much more natural for me.