If studs are spaced at 21 inches on center, how many are needed for a wall 28 feet long?

To determine how many studs are needed for a wall that is 28 feet long with studs spaced at 21 inches on center, it’s necessary to first convert the wall length from feet to inches. There are 12 inches in a foot, so a 28-foot wall is equivalent to 28 x 12 = 336 inches long.

Next, the spacing of the studs is as follows: if they are placed at 21 inches on center, this means that each stud occupies a section of 21 inches, starting at 0 inches and continuing every 21 inches thereafter.

To find the number of spaces between studs in a 336-inch wall, you can divide the total length by the spacing distance:

336 inches ÷ 21 inches = 16.

Since the count of studs includes one at the starting point (0 inches) plus the spaces between them, you will have one additional stud, leading to a total of 16 + 1 = 17 studs required for the entire wall.

This calculation shows that the total number of studs needed for the operation is indeed 17, aligning with the first option.