The average salary of male employees in a firm was $Rs$ $5200$ and that of females was $Rs$ $4200$. The mean salary of all the employees was $Rs$ $5000$. What is the percentage of female employees?

An army lost $10 \%$ of its men in war,$10 \%$ of the remaining due to diseases,and $10 \%$ of the rest were hurt. Thus,the strength was reduced to $729000$ active men. Find the original strength.

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

From the salary of an officer,$10 \%$ is deducted as house rent,$20 \%$ of the rest,he spends on conveyance,$20 \%$ of the rest he pays as income tax and $10 \%$ of the balance,he spends on clothes. If he is left with ₹ $15552$,find his total salary.

When the price of an article is reduced by $15 \%$,the sales increase by $35 \%$. The percentage change in the total amount of receipts is:

$1200$ boys and $650$ girls appeared in an examination. If $70 \%$ of boys and $40 \%$ of girls failed,find the approximate percentage of passed students.