Question

The percentage of metals in a mine of lead ore is $60$. Now the percentage of silver is $\frac{3}{4}$% of metals and the rest is lead. If the mass of ore extracted from this mine is $8000kg$, the mass (in kg.) of lead is:

• A. $4764$
• B. $4762$
• C. $4761$
• D. $4763$

Answer 1

Answer: (A)

Given mass of lead ore $\left(inkg\right)=8000$

Mass of metals in ore $\left(inkg\right)=60\%$of ore.

$=\frac{60}{100}\times 8000=4800$

Mass of silver$=3/4\%$ of mass of metals

$=\frac{3}{4}\times \frac{1}{100}\times 4800=36$

As lead is metal, so

Mass of $Pb=$Mass of metal-Mass of Silver

$=4800-36=4764$