The board of voter registration and elections or other electoral board of any county, city or town in which voting machines are used shall provide for each voting precinct in which such machines are used two sample ballots or instruction ballots, which shall be arranged in the form of a diagram of the entire front of the voting machine as it will appear after the official ballots are arranged therein or thereon for voting on election day. Such sample ballots shall be open to public inspection at such polling place during the day of election.