(adapted from 8.9) the input stream of a stack is a list of all the elements we pushed onto the stack, in the order that we pushed them. the input stream from exercise 8.8 on page 304 of the book for example is abcdefghijklm the output stream is a list of all the elements that are popped off the stack in the order that they are popped off. a. if the input stream is zyxwvutsr, create a sequence of pushes and pops such that the output stream is yxvuwzsrt. b. if the input stream is zyxw, how many different output streams can be created?

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)?