Answer:
Assuming Miguel rolled up his sleeping bag tightly and neatly, the length and circumference of the sleeping bag can help us estimate the length of string needed to tie it up.
Let's say the length of the sleeping bag is 6 feet and the circumference (distance around) is 3 feet. To tie it up, Miguel would need to wrap the string around it 2-3 times, depending on how long the string is and how tight he ties the knot.
So, we can estimate that he used about 12-18 feet of string (i.e. 2-3 times the circumference). In inches, that would be about 144-216 inches of string (i.e. 12-18 feet * 12 inches/foot).
Keep in mind that this is just an estimate and the actual amount of string used may vary depending on the factors mentioned above.
Explanation: