If the width of a side shown in a diagram is specified as 15 inches, what is this width?

The width specified in the diagram as 15 inches is directly stated in the question. This means that when measuring or interpreting the dimensions listed in blueprints or diagrams, the stated measurement indicates exactly that value.

Since the diagram indicates that the width is 15 inches, it reflects the actual dimension without requiring any additional calculations or adjustments. The other values provided in the options do not match the specified width, making them invalid interpretations of the diagram's measurement. This clarity in specifying dimensions is crucial in blueprint reading, as it ensures that all parties involved understand the exact measurements without ambiguity.