A sample $of$ a radioactive substance decayed $to95\mathrm{.}5\%of$ its original amount after a year.

$(a)$ What $is$ the half$-$life $of$ the substance? $(Round$ your answer $to$ two decimal places.$)$

$yr$

$(b)$ How long would $it$ take the sample $to$ decay $to40\%of$ its original amount? $(Round$ your answer $to$ two decimal places.$)$

$yr$