Type stdevp(1, 2, 3, …) for population standard deviation. A list works too: stdevp(L). Standard deviation as a concept is in standard deviation.
Population, not a sample button
ACT lists are usually the whole set, so stdevp matches. Weighted mean is a different leftover, in weighted mean. Mean and median of a plain list are in mean, median, and mode.
The bottom line
stdevp of the whole list. Do not hunt a sample formula unless the stem names a sample.
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