The accuracy of an Electronic Distance Measuring Instrument (EDMI) is specified as ±(a mm + b ppm). Which one of the following statements is correct?
1
Both a and b remain constant, irrespective of the distance being measured.
2
a remains constant and b varies in proportion to the distance being measured.
3
a varies in proportion to the distance being measured and b remains constant.
4
Both a and b vary is proportion to the distance being measured.