$4.$ Consider the following cash flow:

$\backslash$begin$\{$tabular$\}\{|$c$|$c$|\}$

$\backslash$hline Year & Cash Flow $(\backslash$$$)\backslash \backslash$

$\backslash$hline $0$ & $\backslash ($ P $\backslash )\backslash \backslash$

$\backslash$hline $1$ & $1000\backslash \backslash$

$\backslash$hline $2$ & $850\backslash \backslash$

$\backslash$hline $3$ & $700\backslash \backslash$

$\backslash$hline $4$ & $550\backslash \backslash$

$\backslash$hline $5$ & $400\backslash \backslash$

$\backslash$hline $6$ & $400\backslash \backslash$

$\backslash$hline $7$ & $400\backslash \backslash$

$\backslash$hline $8$ & $400\backslash \backslash$

$\backslash$hline

$\backslash$end$\{$tabular$\}$