TDSM 5.3
From The Data Science Design Manual Wikia
[math]B(100, 0.5) \approx N(100 \times 0.5, 100 \times 0.5 \times 0.5) = N(50, 25)[/math]
[math]P(X \leq 70) = 1 - P(X \lt 70) = 1 - P \left( Z \lt \frac{70-50}{25} \right) = 1 - P(Z\lt 0.8) = 1-0.7881 = 0.2119[/math]
