The level of radiation in the control room of a nuclear reactor is to be automatically monitored by a Geiger counter. The monitoring device works as follows: Every tenth minute the number (frequency) .of "clicks" occurring in t seconds is counted automatically. A scheme is required such that, if this frequency exceeds some number c, an alarm will sound. The scheme should have the following properties: If the number of clicks per second is less than 4, there should .be only about 1 chance in 500 that the alam1 will sound. but if the number of clicks reaches 16, there should be only about l chance in 500 that the alarm will not sound. What values should be chosen for t and c?