A power engineer required a 10 ohm, 0.1% tolerance, high power resistor. The only resistors available were 10% tolerance. To achieve the higher tolerance, he uses a series of 100 resistors each of 0.1 ohm. The summing effect was expected to average out the low tolerance, as resistors over and under 0.1 ohm balanced each other out. When the resulting resistance started overheating, the engineer measured the value of each one and plotted a Histogram,