Question $1$

Tee Swift spent USD $$6$ million on her album promotion this month. She expects her new album 'Folk Tales' to sell this many units per month as below:

$\backslash$table$[[$Month$,1,2,3,4,5],[$Sale units,$85,000,65,000,100,000,50,000,50,000]]$

Each album has a recommended retail price of USDS$20.$ Tee Swift would like a return of $12\%$ p$.$a$.$ compounded monthly. From a financial viewpoint, should she release thit album? How long would it take her to recover the album promotion costs? $($For practice purposes, you should use all five techniques: $"$NPV$,$ IRR, PI$,$ PBP$,$ DPBP$"$ discussed in the lecture to attempt this question$)($ans: $NPV=811\mathrm{.}18$;IRR$=70\mathrm{.}34\%\frac{\text{;}}{P}$I $=1\mathrm{.}1352$;$PBP=4$;$DPBP=4\mathrm{.}147)$

How do i find irr?