Calculate the minimum distance from the base of a building to place the base of a portable ladder that is 24 feet long and will be used to access a roof 22 feet high.
Correct Answer
D) 5.5 feet
OSHA requires a 4:1 ratio for ladder placement. Distance = height ÷ 4 = 22 ÷ 4 = 5.5 feet from the base of the building.
Why This Is the Correct Answer
OSHA requires portable ladders to be set up at a 4:1 ratio — for every 4 feet of height, the base must be 1 foot away from the structure. Using the working height of 22 feet (the height the ladder reaches, not its total length): 22 ÷ 4 = 5.5 feet. The 24-foot ladder length is given as a distractor; the placement ratio is based on the working height.
Why the Other Options Are Wrong
Option A: 7 feet
7 feet is too far. Dividing 22 by 4 gives 5.5, not 7. This result might come from incorrectly using the full ladder length (24 ft) or applying a different ratio entirely.
Option B: 6 feet
6 feet results from rounding 5.5 up to the next whole number, which is not required by OSHA's formula. The standard calls for exactly height ÷ 4, which equals 5.5 feet in this case.
Option C: 8 feet
8 feet significantly exceeds the required distance. This may come from dividing by 3 instead of 4, or from using an incorrect working height. Too great a base distance causes the ladder to be too steep and increases fall risk.
Memory Technique
Picture a clock at 1 o'clock position: the ladder leans at 75 degrees, base 1 foot out for every 4 feet up — the '1 o'clock' angle. To find the base distance, just divide the rise by 4. For 22 feet: 22 ÷ 4 = 5.5 ft.
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