$6\mathrm{.}2$

$[0/1$ Points$]$

LARCALC$126\mathrm{.}2\mathrm{.}041.$MI$.$

Radioactive radium has a half$-$life of approximately $1,599$ years. What percent of a given amount remains after $840$ years? $($Round your answer to two decimal places.$)$

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$9.[0/1$ Points$]$

$$ LARCALC$126\mathrm{.}2\mathrm{.}050.$MI$.$

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Find the principal $P$ that must be invested at rate $r,$ compounded monthly, so that $$500,000$ will be available for retirement in $t$ years. $($Round your answer to the nearest cent.$)$

$r=6\%,t=50$

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