Systematic Error from Stretched Ruler Graduations

Steps:

• Recognize the error: Graduations 1% further apart cause consistent underestimation of length, defining systematic error.
• Determine scale factor: Each marked mm represents 1.01 actual mm, so true length exceeds measured.
• Calculate true width: 305 mm × 1.01 = 308.05 mm, rounded to 308 mm.
• Match to options: Systematic type with 308 mm value identifies choice D.

Why D is correct:

• Systematic error is a repeatable bias from faulty calibration; true width formula is measured × (1 + 0.01) = 308 mm.

Why the others are wrong:

• A: Random error is unpredictable variation, not consistent instrument fault; 302 mm reverses the correction.
• B: Systematic type fits, but 302 mm wrongly subtracts 1% instead of adding.
• C: Random type mismatches the consistent bias; 308 mm value is correct but type is wrong.

Final answer: D