A detail drawing shows a wall section at a scale of 1/2" = 1'-0". If a dimension measures 3 inches on the drawing, what is the actual dimension?
Correct Answer
B) 6 feet
At 1/2" = 1'-0" scale, each 1/2 inch on the drawing equals 12 inches actual. Therefore, 3 inches on the drawing equals 3 ÷ 0.5 = 6 feet actual dimension.
Why This Is the Correct Answer
The scale 1/2" = 1'-0" means that every half inch on the drawing represents one foot in reality. To find the actual dimension, we need to determine how many half-inch increments are in 3 inches (which is 6), then multiply by 1 foot each. This gives us 6 feet as the actual dimension.
Why the Other Options Are Wrong
Option A: 3 feet
This would be correct if the scale were 1" = 1'-0", but with 1/2" = 1'-0", the drawing measurement represents twice as much actual distance.
Option C: 18 inches
This answer treats the drawing dimension as if it were actual size (1:1 scale), ignoring the scale factor completely.
Option D: 36 inches
This incorrectly multiplies 3 inches by 12, which would be correct for a 1" = 1'-0" scale, not the given 1/2" = 1'-0" scale.
Memory Technique
Remember 'Half the scale, double the size' - when the drawing scale uses 1/2 inch instead of 1 inch, the actual dimension is twice what you'd get with a 1"=1' scale.
Reference Hint
Look up architectural drawing scales and plan reading in the construction documents section of your reference manual.
More Project Mgmt Questions
What is the minimum R-value required for wall insulation in Florida Climate Zone 2?
A subcontractor brings a new chemical product to your jobsite. Under the Globally Harmonized System (GHS), what information must be immediately available to workers?
A construction site has a trench that is 8 feet deep in Type B soil. What is the maximum allowable slope ratio for the trench walls without protective systems?
A detail drawing shows a scale of 3/4" = 1'-0". If a dimension measures 2.25 inches on the drawing, what is the actual dimension?
What is the maximum recommended spacing between drywall screws when attaching to wood studs?