simpangan baku dari data 5,6,6,8,8,9

→ Rata - rata :
= 5 + 6 + 6 + 8 + 8 + 9 / 6
= 42 / 6
= 7

→ Ragam :
= (5 - 7)² + (6 - 7)² + (6 - 7)² + (8 - 7)² + (8 - 7)² + (9 - 7)² / 6

= (-2)² + (-1)² + (-1)² + 1² + 1² + 2² / 6
= 4 + 1 + 1 + 1 + 1 + 4 / 6
= 12 / 6
= 2

→ Simpangan Baku :
= √ragam
= √2