Contoh Soal Rata-rata dan Solusinya

Tabel nilai ulangan Matematika XI IPA 6 (SMA N 1 Tegal)

Misal rata-rata nilai ulangan XI IPA 6 tuh 8,0. terus ditanya banyaknya anak XI IPA 6 yang dapet nilai 9 berapa ekor? :D


Jawab:
Caranya Hari:
12(7 - 8) + 7(8 - 8) + X(9 - 8) + 2(10 - 8)= 0
-12 + 0 + X + 4.........................................= 0
X...............................................................= 8


Jadi banyaknya anak XI IPA 6 yang mendapat nilai ulangan math 9 adalah 8 ekor... :D


Cara biasa:
((12 x 7) + (7 x 8) + (X x 9) + (2 x 10))/(12 + 7 + X + 2)= 8
(84 + 56 + 9X + 20) / (21 + X)..........................................= 8
(160 + 9X).......................................................................= 8(21 + X)
160 + 9X...........................................................................= 168 + 8X
9X - 8X.............................................................................= 168 - 160
X.......................................................................................= 8


Sama aja kan???
Hehehe, maaf berantakan...


Semoga membantu Anda... ^_^