Question

stiind ca 8 este media ponderată a numerelor 2,5 ;3/5 si x cu ponderile resperctiv 2;5 si 3(4),aflati x

Answer 1

(2,5 * 2 + 3/5 *5 +x * 31/9) : (2+5+31/9) = 8
(5+3+31x/9) : ( 7+31/9)=8
(45+27+31x)/9 : (63+31)/9 = 8
72+31x/ 63+31=8
72+31x = 8*94
72+31x=752
31x = 752-72
31x=680
x=680/31