Question

Tolong yang tau pakai cara.. makasi

Answer 1

Rata2 n siswa = 80
jumlah nilai n siswa = 80 n
rata2 (n-2) siswa = 70
jml nilai (n-2) siswa = 70(n-2) = 70 n - 140
jml nilai tertinggi dan terendah = 200
80 n = 70 n - 140 + 200
80 n - 70 n = 60
10 n = 60
n = 6

Answer 2

Misal jumlah nilai = x, maka :

x/n = 80
x = 80n............................... (1)

x - 200 / n - 2 = 70
x - 200 = 70 (n - 2)
x - 200 = 70n - 140
x = 70n - 140 + 200
x = 70n + 60 ...................(2)

eliminasi persamaan (1) & (2) :
x = 80n dan x = 70n + 60

karna x = x
maka :

80n = 70n + 60
80n - 70n = 60
10n = 60
n = 60/10
n = 6

Jawabannya B

semoga terbantu ;) ,,