Final answer:
Option C. 1/2 inch. Carpenters must drive nails at least ½ inch from the ends or edges of gypsum board when single-nailing. To calculate nail usage, the difference in spring stretching is divided by the initial stretch, indicating that 40% or 2/5 of the nails in the box were used.
Step-by-step explanation:
When carpenters use single-nailing for gypsum board, they must drive nails at least ½ inch from the ends or edges of the board. Hence, the correct answer is C. ½ inch. When we consider the weight of a large box of nails being measured by the displacement of a spring, we need to use the proportion of the spring's stretching to determine the usage of nails during the day. If the spring stretched 50 cm initially and 30 cm at the end of the day, the difference in stretching (50 cm - 30 cm = 20 cm) represents the nails used. Divided by the initial measurement (20 cm / 50 cm), it shows that 40% or 2/5 of the nails have been used.
When using single-nailing to secure gypsum board, it is recommended to drive nails at least 1/2 inch from the ends or edges. This distance helps prevent the gypsum board from cracking or breaking due to stress or movement. By driving the nails at least 1/2 inch from the ends or edges, you ensure a secure installation without compromising the integrity of the board.