Answer: 11.9 cm
Work Shown:
|x-12.2| = 0.3
x-12.2 = -0.3 or x-12.2 = 0.3
x = -0.3+12.2 or x = 0.3+12.2
x = 11.9 or x = 12.5
The min length is 11.9 cm and the max length is 12.5 cm
Subtracting 12.2 from either x value leads to a positive difference of 0.3 which is the margin of error.
