Answer :

The range in a set of numbers is the difference between the largest and smallest values. To find the range of the given lengths, we follow these steps:

1. Identify the smallest and largest numbers in the list.
2. Subtract the smallest number from the largest number.

Let's proceed with these steps given our lengths:

12.1 cm, 19 cm, 7.2 cm, 0.5 cm, 9.9 cm, 20 cm

1. The smallest length in the list is 0.5 cm.
2. The largest length in the list is 20 cm.

Now we subtract the smallest length from the largest length to get the range:

Range = Largest length - Smallest length

Calculation:
Range = 20 cm - 0.5 cm
Range = 19.5 cm

Therefore, the range of the given lengths is 19.5 cm.