Final answer:
The question mistake's roofing nails' purpose, but the math concerns the proportion of nails used, calculated from the stretch of a spring.
Step-by-step explanation:
This statement is incorrect; roofing nails are not intended to wick moisture but to securely fasten roofing materials to the sheathing. However, the actual mathematical question involves calculating the fraction or percentage of nails used based on the spring's stretch measurements from a box of nails at two different times.
At the beginning of the day, the box caused the spring to stretch 50 cm, and at the end of the day, the spring stretched 30 cm. Given the starting stretch of 50 cm represents the total number of nails, a 20 cm reduction indicates that 2/5 of the nails were used, as 20 is 2/5ths of 50. In percentage terms, this is 40% of the nails.