In physics, whenever you make a measurement it has a precision. Usually you represent this as a normal distribution, but for calculations it can be easier to represent this as an interval.

The police measure the distance my car travelled [ 99.9, 100.1 ] m and the time it took [ 3.3, 3.4 ] s - how fast was my car going? [29.38, 30.33] m/s according to the interval calculator.

Physics students learn exactly this method before they move on to more sophisticated analysis with error distributions.

And one might want to approximate error distribution calculus with a method that will look like the one here