Ajay working in a Cellular company as a salesman. His monthly salary is Rs. 200. But he gets bonus as per given rule. If he sells sim cards of Rs. X then his bonus will be $$\left[ {{{\left( {\frac{x}{{100}}} \right)}^2} + 10} \right]$$   . In the first quarter of the year his average sale was Rs. 3000 per month. In the next 5 five month his average sale was Rs. 5000 per month and for next four month his average sale was Rs. 8000 per month. What is the average earning per month for the whole year?

$$\eqalign{ & {\text{Bonus}}\,{\text{for}}\,{\text{the}}\,{\text{first}}\,{\text{three}}\,{\text{month}}, \cr & = \left[ {{{\left( {\frac{{3000}}{{100}}} \right)}^2} + 10} \right] \times 3 \cr & = Rs.\,2710 \cr & {\text{Bonus}}\,{\text{for}}\,{\text{the}}\,{\text{next}}\,{\text{five}}\,{\text{month}}, \cr & = \left[ {{{\left( {\frac{{5000}}{{100}}} \right)}^2} + 10} \right] \times 5 \cr & = Rs.\,12550 \cr & {\text{Bonus}}\,{\text{for}}\,{\text{the}}\,{\text{next}}\,{\text{four}}\,{\text{month}}, \cr & = \left[ {{{\left( {\frac{{8000}}{{100}}} \right)}^2} + 10} \right] \times 4 \cr & = Rs.\,25640 \cr & {\text{Total}}\,{\text{earning}}\,{\text{as}}\,{\text{bonus}}\,{\text{for}}\,{\text{whole}}\,{\text{year}}, \cr & = 2710 + 12550 + 25640 \cr & = Rs.\,40900 \cr & {\text{His}}\,{\text{average}}\,{\text{bonus}} \cr & = \frac{{40900}}{{12}} = Rs.\,3410 \cr & {\text{Thus}}\,{\text{his}}\,{\text{average}}\,{\text{earning}}\,{\text{for}}\,{\text{whole}}\,{\text{year}}, \cr & = 3410 + 200 \cr & = Rs.\,3610 \cr} $$