Standard industry practice when estimating the number of studs needed is to allow one stud per each 24'' wall length one stud per each 12'' of wall length one stud per 16'' of wall length one stud per each 9" of wall length

The correct answer is: one stud per $16''$ of wall length.<br /><br />In standard industry practice, when estimating the number of studs needed for framing walls, it is common to allow one stud for every $16''$ of wall length. This is a general guideline used in construction to ensure adequate structural support and stability for the walls. The spacing of the studs may vary depending on the specific requirements of the project, the type of wall being constructed, and other factors such as the thickness of the wall, the type of insulation being used, and the overall design of the building. However, the $16''$ on-center spacing is a commonly used standard in residential and light commercial construction.