Maybe even more important than how much they weigh is that the plates used in weightlifting be the same weight.
When one of each weight is hanging on opposite ends of a bar, they need to balance. A random sample of twenty-four 25-lb weights used for weightlifting were randomly selected and their weights (in pounds) determined:

There have been complaints about the excessive variability in the weights of these 25-lb plates. Does the sample show sufficient evidence to conclude that the variability in the weights is greater than the acceptable 1-lb standard deviation? Use a = 0.01

25.3 22 25.7 24.2 25.7 23.9 23. 21.9 24.7 26.3 26.5 22.2 25.9 23.5 25.8 27.1 25.4 22.0 25.2 21 27.9 22.9 27.3 25.7