Question

Hand-span and cubit cannot be used as standard units of length. Why?

Answer 1

1. Hand-span is the maximum distance between the tips of the thumb and little finger, cubit is equal to the length of a forearm.
2. The length of the body parts is different for different people. So, hand-span and cubit cannot be used as a standard unit of measurement.
3. For uniformity and convenience, standard units of measurement are mandatory.