All you have to do is learn Chebyshev's theorem in terms of k, then substitute 2 for k. Here is Chebyshev's theorem in terms of k: According to Chebyshev's theorem, the proportion of values from a data set that is further than standard deviations from the mean is at most . Then when you plug in 2 for k, you get: According to Chebyshev's theorem, the proportion of values from a data set that is further than standard deviations from the mean is at most . or writing for , According to Chebyshev's theorem, the proportion of values from a data set that is further than standard deviations from the mean is at most . Or if you prefer a decimal answer: According to Chebyshev's theorem, the proportion of values from a data set that is further than standard deviations from the mean is at most . Or if you prefer a percent answer: According to Chebyshev's theorem, the proportion of values from a data set that is further than standard deviations from the mean is at most %.