Question

Daca media aritmetica ponderata a numerelor 2,4; x si 4 cu ponderile x; 0,2 si 0,(6) este 2, aflati-l pe x.

Answer 1

[2,4x+x×0,2+4×0,(6)]/[x+0,2+0,(6)]=2
0,(6)=6/9=2/3
(24x/10+2x/10+4×2/3)/(x+1/5+2/3)=2
(12x/5+x/5+8/3)/(x+3/15+10/15)=2
(13x/5+8/3)/(x+13/15)=2
13x/5+8/3=2x+26/15
39x+40=30x+26
9x=-14
x=-14/9=-1,(5)