Hi$,$ could you please explain how I would calculate this and what I should put into my calculator:

A newly constructed $30-$floor hotel if opened now time $=0$ could begin to yield an annual rental income of $6m$ from year $0.$ Alternatively, the building could be extended by one extra floor being added at a cost of $19m$ incurred in year $0,$ though this would mean that the hotel would be unoccupied in year $0$ and all revenues for that year would be lost. The revenue from the extra floor would amount to $1\mathrm{.}5m$ per year in all years $1$ to $20$ after which the building will be worthless.

$($i$)$ In terms of the decision to construct the extra floor, sketch a time line $($years $0$ to $20)$ of the cash flows.

$($ii$)$ Show with clear workings that the internal rate of return of adding the extra floor is between $1\%$ and $2\%.$ You may use the tables provided.