Question

Stiind ca 4,9 este media ponderata a numerelor 4,12,4/9 si x avand respectiv ponderile 6,9,18 si 7 aflati-l pe x

Answer 1

(4*6+12*9+4/9*18+x*7)/(6+9+18+7)=4,9
(24+108+8+7x)/(40)=4,9
(140+7x) :40=4,9
140+7x=4,9*40
140+7x=196
7x=196-140
7x=56
x=56:7
x=8