Answer: No. Mr. Smith cannot run for the Massachusetts Senate seat
Explanation:
From the question, we are informed that Mr. Smith is 49 years old, a United States citizen and that he would like to run for a Senate seat in Massachusetts. He lives in New York and is registered to vote in that state.
It should be noted that Mr Smith isn't a resident of Massachusetts and therefore, he cannot run for Senator as he's not registered there but rather he registered in New York. Assuming he registered in New York, then he can be a senator there but he isn't registered there, therefore he can't.