A shot in the dark(phrase)
(An act whose outcome cannot be foreseen; a guess.)
Hindi meaning:एक कार्य जिसके परिणाम का अनुमान नहीं लगाया जा सकता
Synonyms: Guess, Approximation, Assumption, Surmise, Supposition, Conjecture, Speculation
Antonyms: Certainty, Absolutely, Back To The Bone, Certitude, Unequivocally
Example: Well, this is just a shot in the dark, but I'm going to say that the answer to the question is 50.
Trick to remember: Dark me shot A shot in the dark hi lagta hai. 
