Question

Buna. as vrea si eu rezolvarea problemelor....

Answer 1

3. 
a) $m_{a} = \frac{3,2+0,8}{2} = \frac{4}{2} = 2$
b) $m_{a} = \frac{1,16+3,28+4,26}{3} = \frac{8,7}{3} = 2,9$

4.
a+b=6,75
a=2b
2b+b=6,75
3b=6,75
b=2,25 ⇒ a=6,75-2,25 ⇒ a=4,5

5.
$\frac{a+b+c}{3} = 2,5$
a=0,7+b
b=2c ⇒ c=$\frac{b}{2}$

a+b+c=7,5
0,7+b+b+$\frac{b}{2}$=7,5
0,7+$\frac{2b+2b+b}{2} = 7,5$
$\frac{5b}{2} = 6,8$
5b=13,6 ⇒ b=2,7 ⇒ a=0,7+2,72 ⇒ a=3,42 
              ⇒ c=$\frac{2,72}{2}$ ⇒ c=1,36

6.
Mihai a cumparat:
3,5kg portocale
2,4kg mere
1,8kg struguri

A platit:
1kg portocale........4 lei
3,5kg portocale.....x lei
x=3,5×4=14 lei

1kg mere...............3,5 lei
2,4kg mere............y lei
y=2,4×3,5=8,4 lei

1kg struguri...........6 lei
1,8kg struguri........z lei
z=1,8×6=10,8 lei

Suma totala a fructelor este:
14+8,4+10,8=33,2 lei

Restul primit de Mihai este:
100-33,2=66,8 lei