Two machines produce steel rods of the same target length of 50 mm.
Machine A: standard deviation = 0.20 mm, range = 4 mm
Machine B: standard deviation = 0.50 mm, range = 2 mm
Which statement about the consistency of rod lengths is correct?
(a) Machine B is more consistent because it has the smaller range.
(b) Machine A is more consistent because it has the smaller standard deviation.
(c) Both machines are equally consistent because each has one small measure of spread.
(d) Consistency cannot be compared unless their means are different.