Final answer:
Taking the average of more measurements and calibrating the instrument decreases the random error, while taking fewer measurements increases it.
Step-by-step explanation:
Taking the average of more measurements and calibrating the instrument decrease the random error of a measurement, while taking fewer measurements increases the random error.
When taking the average of more measurements, the random errors tend to cancel out, resulting in a more accurate measurement. This is because random errors vary from one observation to another, but when multiple measurements are taken, the random errors have an equal chance of being positive or negative, leading to their cancellation.
On the other hand, calibrating the instrument helps reduce systematic errors, which contribute to the random error. Systematic errors are constant and have the same value in every measurement. By calibrating the instrument, these systematic errors can be identified and reduced, leading to a decrease in random error.