The time that it takes a driver to react to the brake lights on a decelerating vehicle is critical in helping to avoid rear end collisions. A study found that the reaction time for an in traffic reponse to a brake signal from standard brake lights can be modeled with a normal distribution with a mean of 1.25 secs and standard deviation of 0.45 sec  what percent of drivers have a reaction time between 0.

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.