Răspuns:
15%+25%+20%+10%=70%
[tex]\frac{70}{100} =\frac{28}{x}[/tex]
x=2800:70 x=40 elevi in clasa
5%·40=5:100·40=2 elevi nota 3
5%·40=5:100·40=2 elevi nota 4
10%·40=10:100·40=4 elevi nota 5
10%·40=10:100·40=4 elevi nota 6
15%·40=15:100·40=6 elevi nota 7
25%·40=25:100·40=10 elevi nota 8
20%·40=20:100·40=8 elevi nota 9
10%·40=10:100·40=4 elevi nota 10
(2·3+2·4+4·5+4·6+6·7+10·8+8·9+4·10):40=(6+8+20+24+42+80+72+40):40=292:40=7.30
Explicație pas cu pas: