A sample of 2000 observations has a mean of 74 and a standard deviation of 12. Using Chebyshev’s theorem, find at least what percentage of the observations fall in the intervals x̅ ± 2s, x̅ ± 2.5s, and x̅ ± 3s. Here x̅ ± 2s represents the interval x̅  – 2s to x̅ + 2s, and so on.