Given that,
The length of ribbon= 36 inch
We know, if Shelia wants to divide the ribbon in 5 equal parts, she needs to divide the length of the ribbon by 5.
So,
The length of the 5 equal parts of the ribbon= 36/5= 7.2 inch
But Shelia got each pieces length equals to 7 inches.
So, There is an error of (7.2-7) 0.2 inches in her calculation.