4.
50 t = 50000 kg sare gema
5000 kg sunt impuritati
m.pura = m.impura - m.impuritati
= 50000 - 5000 = 45000 kg
100% .................................... 50000 kg impuri
p% ...................................... 45000 kg puri
= 90%
sau
p% = m.purax100/m.impura
= 45000x100/50000 = 90%
5.
m.impura = 2750 kg zahar
p% = 90%
100% .............................. 2750 kg zahar impur
p=90% ........................... m = 2475 kg zahar pur
m.impuritati = m.impura - m.pura
= 2750 - 2475 = 275 kg impuritati
6.
100% impur - 90% pur = 10% impuritati
10% .................................... 0,03 g impuritati
100% .............................. m = 0,3 g masa impura supusa analizei
=> m.pura = m.impura - m.impuritati
= 0,3-0,03 = 0,27 g
