Why does a medical thermometer only measure between 30 and 40?

Answer 1

A thermometer can be read with greater accuracy if limited to a smaller temperature range. So a medical thermometer with a range from 30o Centigrade (or Celsius) to 40o Centigrade, covering a range of only 10 degrees, will display the degree intervals as larger segments, which can be more accurately read and also fractionally subdivided. And since normal human body temperature is 36.8oC and core body temperatures outside the 30oC - 40oC range are almost never found in a living person, the 30o-40o range is sufficient.