Adding to what eftalgezer said:
Basically when you have a "the X of the Y" construction, you're going to have to say: "Y-[n]-in X-[s]-i"
The letters in brackets will be necessary in case Y or X end in a vowel.
So for this example: 60 % of the doctors
→ (doctors)-[n]-in (60 %) -[s]-i
(doktorlar)-[n]-in (yüzde altmış)-[s]-i
Neither 'doktorlar' nor 'yüzde altmış' ends in a vowel, so the letters in the brackets are unnecessary. After applying the vowel harmony, you get: Doktorların yüzde altmışı.
Exactly. You didn't add genitive to "altın" (gold), which makes it indefinite: the price of "gold (in general)". In that case, it's translatable as "The gold price", - 'the' referring to 'price'.
If you wanted to say "the price of THE gold (that I have here)", you would have to add "-ın" to "altın" → Altının fiyatı
I wrote "Sixty out of one hundred doctors are male", and my answer was rejected as it should read "sixty %". Why is "out of one hundred" incorrect for "yüzde"? (And, yes, Ruth and AlexinNotTurkey, the proposed correct answer contained an underlined "the" doctors indicating (to me) that DL considers omission of "the" an error.)