Professor Bloop has another one of his insane experiments in progress. He is designing a machine to remove the shells from hard-boiled eggs all in one piece. He makes a voltage measurement at terminal 23B on his machine and finds it at -5.2 volts. "Amazing!" he exclaims "that is exactly half the voltage I measured yesterday before I put in a larger foubister!" What voltage did he measure on terminal 23B yesterday before he changed the filibuster