When you say that someone is 1.90 m tall what you're actually saying is that their height is given by a random variable whose expected value is 1.90 m. Usually

When you say that someone is 1.90 m tall what you're actually saying is that their height is given by a random variable whose expected value is 1.90 m. Usually that random variable is a Gaussian with a very small standard deviation. In case of human height perhaps 0.005 m since height varies slightly during the day and measurements are inexact. Saying the request rate is 4 Hz works the same, except here the random variable (probably) is Poisson distributed with expected value 4.