途中 and 半ば: partway through and around the middle
Compare a ringing phone during work with a question midway through a talk, without converting 途中 into an exact halfway point.
During progress or a journey
途中, read とちゅう, identifies a point during progress or travel. 作業の途中で電話が鳴りました。 says that the phone rang during the work.
駅へ行く途中で友達に会いました。 says that a friend was met on the way to the station. It does not establish an exact halfway location.
Around the middle or halfway
半ば, read なかば, can identify the middle part or roughly half. 話の半ばで質問が出ました。 says that a question arose around the middle of the talk.
四月半ばに引っ越す予定です。 plans a move around the middle of April. 半ば alone does not fix a particular date.
Partial progress and its measure
本を途中まで読みました。 says that the book was read partway through. It gives no figure of fifty percent of the pages.
作業は半ばまで進みました。 says that the work progressed about halfway. Check whether the measure is page count, workload, or something else.
Does 本を途中まで読みました。 mean exactly half the book was read?
Show the answer and why
No. It says that the book was read partway through, without specifying an exact proportion.