Here are weights of recently produced sinks: 20.8, 20.9, 19.5, 20.8, 20.0, 19.8, 20.1, 20.5, 19.8, 20.3, 20.0, 19.7, 20.3, 19.5, 20.2, 20.2, 19.5, 20.5 Find the usual summary measure that tells approximately how far from average these weights are.