Jika mean data di bawah ini adalah 16,25, tentukan nilai x. NILAI F 1-5 3 6-10 6 11-15 x 16-20 10 21-25 14

Titik tengah kelas ,= 3, 8, 13, 18, 23
frekuensi berturut-turut : 3, 6, ,x, 10, 14
Mean = ( jumlah semua ukuran) : banyak ukuran
16,25 = (3x3 + 8x6 + 13 x + 18x10 + 23x14) / (33 + x )
(9+ 48+13x +180+322) /(33+x) = 16,25
(559 + 13x) / (33+x) = 16,25
559+ 13x = 536,25 - 16,25x
559- 536,25 = 16,25x - 13x
3,25x = 22,75
x = 22,75/3,25.
x = 7

Nilai.......Nilai..........F.....Nilai
................Tengah............Tengah × F
--------------------------------------------------
1 - 5.............3..........3.............9
6 - 10..........8...........6............48
11 - 15.........13...........x............13x
16 - 20.......18...........10..........180
21 - 25.......23..........14..........322
--------------------------------------------------
Jumlah................33 + x...559 + 13x
--------------------------------------------------

Mean = (Nilai tengah × F)/F
16,25 = (559 + 13x)/(33 + x)
559 + 13x = 16,25 × (33 + x)
559 + 13x = 536,25 + 16,25x
559 - 536,25 = 16,25x - 13x
22,75 = 3,25x
x = 22,75/3,25
x = 7

Jadi nilai x adalah 7