tolong kk beri jalan ya kk. bantu dong!

xi ..... f ....... fk
65 ... 3 ...... 3
70 ... 5 ...... 3 + 5 = 8
75 ... 10 .... 8 + 10 = 18
80 ... 9 ..... 18 + 9 = 27
85 ... 8 ..... 27 + 8 = 35
90 ... 5 .... 35 + 5 = 40

p = 70 - 65 = 5

Kuartil bawah = Q1 = 1/4 n = 1/4 (40) = 10 => ada di fk = 18
tb = (75 + 70)/2 = 72,5
fks = 8 => fk sebelum 18
f = 10
Q1 = tb + [1/4 n - fks)/f . p
= 72,5 + [10 - 8]/10 . 5
= 72,5 + 2/10 . 5
= 72,5 + 1
= 73,5

Kuartil atas = Q3 = 3/4 n = 3/4 (40) = 30 => ada di fk = 35
tb = (85 + 80)/2 = 82,5
fks = 27 => fk sebelum 35
f = 8
Q3 = tb + [3/4 n - fks]/f . p
= 82,5 + [30 - 27]/8 . 5
= 82,5 + 3/8 . 5
= 82,5 + 1,875
= 84,375