Question

Nilai suatu data :
No. Nilai Frekuensi
1. 11 8
2. 14 6
3. 18 12
4. 21 8
5. 24 X ?
6. 27 6

Jika data diatas memiliki rata rata 18,66. Maka tentukan nilai x ?

a. 8 d. 16
b. 10 e. 20
c. 14

Answer 1

Jawab : 
1) Hitung total
Total Nilai
(11*8) + (14*6) + (18*12) + (21* 8) + (24*x) + (27*6)
= 88 + 84 + 216 + 168 + 24x + 162
= 718 + 24x

Total Frekuensi = 8+6+12+8+x+6
= 40 + x

2) Mean = 18,66
Mean = Total nilai / Total frekuensi
18.67 = 718 + 24x / 40 + x
746.67+18.67x = 718+24x
28.67 = 5.33x
x = 28.67/5.33
x = 5.375