For the cash flow series shown below:

a$.$ Determine the number of possible i values using the two sign tests

b$.$ Find the EROR using the MIRR method with an investment rate $($i$)$ of $18\%$ per year and a borrowing rate $($is$)$ of $10\%$ per year

Year

Revenue, S

Costs, S

$0$

$0$

$-6,000$

$1$

$25\mathrm{.}000$

$2$

$-30,000-7,000$

$3$

$4,000$

$-6,000$

$4$

$28,000$

$19,000$

$-12\mathrm{.}000$