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 % of female employees?

Let there be $$x$$ males and $$y$$ females in the firm

=> Total male salary = Rs. $$5200x$$

Similarly, total females salary = Rs. $$4200y$$

Thus, total salary = $$5200x+4200y=5000(x+y)$$

=> $$5200x+4200y=5000x+5000y$$

=> $$5200x-5000x=5000y-4200y$$

=> $$200x=800y$$

=> $$\frac{y}{x}=\frac{200}{800} = \frac{1}{4}$$

$$\therefore$$ % of female employees = $$\frac{y}{x+y} \times 100$$

= $$\frac{1}{5} \times 100=20\%$$

=> Ans - (B)