Resistances in a population of wires are normally distributed with mean 20 mΩ and standard deviation 3 mΩ. The resistance of two randomly chosen wires are 23 mΩ and 16 mΩ. Convert these amounts to standard units.
A resistance of 23 mΩ is 3 mΩ more than the mean of 20, and 3 mΩ is equal to one standard deviation. So 23 mΩ is one standard deviation above the mean and is thus equivalent to one standard unit. A resistance of 16 mΩ is 1.33 standard deviations below the mean, so 16 mΩis equivalent to -1.33 standard units.