diff --git a/education/statistics/Probability.md b/education/statistics/Probability.md
index 59062b8..60f92e8 100644
--- a/education/statistics/Probability.md
+++ b/education/statistics/Probability.md
@@ -76,4 +76,6 @@ m
 The *expected value*(EV) for the *sum* of all draws is $num_{draws}*ave_{box}$. 
 The *standard error* (SE) for the sum of all draws is $\sigma_{box} \sqrt{num_{draws}}$
 
-68% of the data will be within +- 1 SE of the EV.
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+68% of the data will be within +- 1 SE of the EV.
+
+to find the % of data between two points, find $z_1$ and $z_2$, then $normalcdf(z_1, z_2)$ and multiply by 100%
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