mohon bantuan nya no 35

simpangan / d = -5, 0, 5, 10, 15, 20
Sigma f.d = (9.- 5 + 12.0 + 14.5 + 16.10 + 14.15 + 10.20 )
= (-45 + 0 + 70 + 160 + 210 + 200)
= 595
rata rata = 47 + 595/75