This is an Excel Tool that visually demonstrates the Central Limit Theorem on a large set of data. The simulation generates exponentially distribution failure data which is typically seen in electronics and complex repairable systems. The Mean-Time-Between-Failure (MTBF) is calculated for each of the 301 simulation runs. Each simulation run has 107 data points. The simulation data is formatted using the Conditional Format feature to add a visual test of randomness to the data set. The exponential curve is plotted along with a histogram of the Mean-Time-Between-Failures superimposed on the exponential plot. This shows that although the underlying distribution is Exponential, the distribution of the MTBF is approximately normal, in line with the Central Limit Theorem.