Tolong dibantuu gan...

* mean = (8+9+6+10+12+15)/6
= 60/6
= 10

* Simpangan baku :
= √ ((8-10)² + (9-10)² + (6-10)² + (10-10)² + (12-10)² + (15-10)²)/6

= √ ( (-2)²+(-1)²+(-4)²+(0)²+2²+5²)/6
= √ (4+1+16+0+4+25)/6
= √ 50/6
= √ 25/3
= 5 √ 1/3