The input and output signals of a system is related by the following equation: fraction numerator d squared y over denominator d t squared end fraction plus sin (3 y )fraction numerator d y over denominator d t end fraction plus y equals t fraction numerator d f over denominator d t end fraction plus f. Then, the system is:

An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?