Jawabanmu

2014-06-05T08:41:06+07:00
40 x 5,1 = 204
39 x 5,0 = 195
204-195 = 9
2014-06-05T14:53:55+07:00
Mean=jumlah data/banyak data
5,1=5x39+x/40
204=195+x
204-195=x
9=x