$1.$ We sometimes need to find how long it will take a sum of money $($or anything else$)$ to grow to some specified amount. Note that you should enter PV as a negative and FV as a positive.

$($a$)$ For example, if a company$$s sales grow at a rate of $4\mathrm{.}2\%$ per year, how long will it take to double? Show your answer to $2$ decimals $($x$.$xx years$).$ If you are unsure how to work this, return to this week$$s practice problems.

You do not need any additional data to solve this problem. If you are in doubt here, go back to the lecture notes and practice problem $6$ where double$/$tripling is discussed. Read the notes!