please bantu jawab yahh pakai cara no 36

jawb

n1 = banyak laki laki
n2 = banyak perempuan
x1 = rata laki = 164
x2 = rata perrempuan = 156
xg = rata gabungan  = 162

(n1+n2) xg = n1. x1 + n2 x2
(n1+n2) 162 = n1(164) + n2(156)
n2(162 - 156) = n1(164 -162)
6 . n2 = 2. n1
n1 : n2 = 2 : 6 = 1: 3

x1 = 164
x2 = 156
x. gab = 162

dit → n1 : n2 ??

jawab :

(n1 + n2) 162 = 164 × n1 + 156 × n2
162 n1 + 162 n2 = 164 n1 + 156 n2
162 n2 - 156 n2 = 164 n1 - 162 n1
6 n2 = 2 n1
3 n2 = 1 n1
★ (dibalikkan karena yang ditanyakan perbandingan n1 : n2, tetapi jumlah tidak dibalikkan....) ★
3 n1 = 1 n2
→→ 3 : 1 ←← C.

semoga membantu........