${?}_{{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{9.}\text{W}\text{h}\text{i}\text{c}\text{h}\text{o}\text{n}\text{e}of\text{t}\text{h}\text{e}\text{f}\text{o}\text{l}\text{l}\text{o}\text{w}\text{i}\text{n}\text{g}\text{s}\text{t}\text{a}\text{t}\text{e}\text{m}\text{e}\text{n}\text{t}\text{s}is\text{c}\text{o}\text{r}\text{r}\text{e}\text{c}\text{t}\text{c}\text{o}\text{n}\text{c}\text{e}\text{r}\text{n}\text{i}\text{n}\text{g}\text{t}\text{h}\text{e}\text{p}\text{r}\text{o}\text{f}\text{i}\text{t}\text{a}\text{b}\text{i}\text{l}\text{i}\text{t}\text{y}\text{i}\text{n}\text{d}\text{e}\text{x}(PI)?}$

$a.$ Projects with positive $NPV$ will have negative $PI.$

$b.PIis$ the discount rate that makes the net present value equal $to$ zero.

$c.$ There can $be$ multiple PIs $if$ the cash flows are unconventional.

$d.PIis$ used $to$ rank positive $NPV$ projects when the available funds are $limited.$