Question

Accuracy and Precision.

Trooper Watkins uses a measuring wheel (image at right) to measure the distances involved in traffic accidents. One rotation of the wheel is supposed to be 36 inches, but it is really only 35 7/8 inches.

Trooper Watkins’ new digital measuring wheel has an LED that gives reading to a tenth of an inch. His old mechanical measuring wheel, which was also supposed to be 36” in circumference, was really 36 1/4”. Its analog readout showed measurements in 1⁄4 inch increments.

Which one (new digital or old analog) is more precise? WHY? Which one (new digital or old analog) is more accurate? WHY?

Answer 1

(first part)since the increment in new digital=1/10=0.1 is less than increment in old analog is 1/4=0.25, so new digital is more precise.

(second part) error in old analog=|36-35.875|=0.125

error in new digital=|36-36.25|=0.25

since the error in old analog is less, so it is more accurate