Răspuns:
a) [tex]\frac{41}{108}[/tex]
b) 2.155
c) 1.58(3)
d) 1.07
Explicație pas cu pas:
a) [tex]m_{a}[/tex] = ([tex]\frac{1}{6} + \frac{2}{9} +\frac{3}{4}[/tex]) ÷ 3 (acum inmultim prima fractie cu 6, a doua cu 4 si a treia cu 9)
[tex]m_{a}[/tex] = ([tex]\frac{6}{36} + \frac{8}{36} + \frac{27}{36}[/tex]) ÷ 3
[tex]m_{a}[/tex] = [tex]\frac{41}{36}[/tex] ÷ 3 = [tex]\frac{41}{36}[/tex] × [tex]\frac{1}{3}[/tex] = [tex]\frac{41}{108}[/tex]
b) [tex]m_{b}[/tex] = ([tex]\frac{3}{7} + \frac{1}{5} + 2 + 6[/tex]) ÷ 4
[tex]m_{b}[/tex] = (0.42 + 0.2 + 2 + 6) ÷ 4 = 8.62 ÷ 4 = 2.155
c) [tex]m_{c}[/tex] = (1.2 + 0.15 + 3.4) ÷ 3
[tex]m_{c}[/tex] = 4.75 ÷ 3 = 1.58(3)
d) [tex]m_{d}[/tex] = [1.(5) + 0.1(5) + 1.5] ÷ 3
[tex]m_{d}[/tex] = ([tex]\frac{14}{9} +\frac{14}{90} +\frac{15}{10}[/tex]) ÷ 3
[tex]m_{d}[/tex] = ([tex]\frac{140}{90} +\frac{14}{90} +\frac{135}{90}[/tex]) ÷ 3
[tex]m_{d}[/tex] = ([tex]\frac{289}{90}[/tex]) ÷ 3 = [tex]\frac{289}{90}[/tex] × [tex]\frac{1}{3}[/tex] = [tex]\frac{289}{270}[/tex] = 1.07
