Answer:
Kate has changed the unit of measurement from centimeters to decimeters.
Explanation:
Tony measures a drum stick and the length is measured to be 31 centimeters.
Now, Kate converts Tony's measurements and gets 3.1.
Now, we know that 10 centimeters are equivalent to 1 decimeter.
Hence, 1 centimeter will be equivalent to 0.1 decimeters.
And, 31 centimeters will be equivalent to 31 × 0.1 = 3.1 decimeters.
So, Kate has changed the unit of measurement from centimeters to decimeters. (Answer)