A student repeats an experiment to measure the distance from a convex lens to a screen where a sharp image is formed.
The distance between the object and the lens is kept constant. The four measurements obtained for the image distance are: 15.2 cm,14.8 cm,15.6 cm,14.4 cm15.2\text{ cm}, \quad 14.8\text{ cm}, \quad 15.6\text{ cm}, \quad 14.4\text{ cm}15.2 cm,14.8 cm,15.6 cm,14.4 cm
Calculate the uncertainty in these measurements.