Tom's job was to test light sensors for the Navy. He would mount 4 sensors at a time in a test circuit, then shine a light at them and measure the output.
"Sensor #157 is clearly the best," Tom concluded. "It's signal is weak, but the relative noise is 42% lower than any of the other sensors on the board. That's really amazing!"
"I can tell right away you've made a mistake," said Tom's boss.
What was Tom's mistake?
- Tom's boss doesn't know any more than we do.
- 42% (not 41% or 43%) must be the key clue to the answer.
- Some knowledge of electronics is involved. But it doesn't matter how you explain the electronics so long as you can say where 42% comes from.