• question_answer There are 45 male and 15 female employees in an office. If the mean salary of the 60 employees is Rs. 4800 and the mean salary of the male employees is Rs. 5000, then the mean salary of the female employees is A)  Rs.4200          B)  Rs.4500                      C)  Rs.5600         D)         Rs.6000

Given that, Number of male employees (M) = 45 Number of female employees (F) =15 Mean salary of male employee $\left( {{{\bar{x}}}_{M}} \right)$ =Rs. 5000 Total number of employees $=(M+F)$                         $=45+15=60$ Mean salary of employees $\left( {{{\bar{x}}}_{MF}} \right)=Rs.\,4800$ Let mean salary of female employee is ${{\bar{x}}_{F}}$ By formula, ${{\bar{x}}_{MF}}=\frac{M\,\,{{{\bar{x}}}_{M}}+F\,{{{\bar{x}}}_{F}}}{60}\,\,\,\,$ $\Rightarrow$      $4800=\frac{45\times 5000+15\times {{{\bar{x}}}_{F}}}{60}$ $\Rightarrow$            $4800\times 60-45\times 5000=15\times {{\bar{x}}_{F}}$ $\therefore$                ${{\bar{x}}_{F}}=4800\times 4-3\times 5000$             $=300(16\times 4-50)=300\times 14=4200.$