NPV and IRR

Consider a project with the following cash flows:

The appropriate discount rate of the project is $9\%.$

$($a$)$ What is the Net Present Value of the project? Based on the NPV decision rule, should we invest in this

project?

$($b$)$ Next, we want to see the dependence of NPV on the discount rate. Plot the NPV for discount rates

in a range of $0\%$ to $40\%$ with an increment of $5\%.$ How many estimates of IRR do we expect for this

project?

$($c$)$ Find the IRR using the Excel function "IRR$()".$ As the initial guess, please try $1\%$ and $30\%.$ Based on

the IRR decision rule, can we determine whether to invest or not?