CS$-205-$ CHALLENGE ACTIVITY

$6\mathrm{.}2\mathrm{.}1$: Caffeine levels.

A half$-$life is the amount of time it takes for a substance or entity to fall to half its original value. Caffeine has a half$-$life of about $6$ hours in humans. Given caffeine amount $($in mg$)$ as input, output the caffeine level after $6,12,$ and $18$ hours.

Ex: If the input is $100,$ the output is:

After $6$ hours: $50\mathrm{.}0$ mg

After $12$ hours: $25\mathrm{.}0$ mg

After $18$ hours: $12\mathrm{.}5$ mg

Note: A cup of coffee has about $100$ mg$.$ A soda has about $40$ mg$.$ An "energy" drink $($a misnomer$)$ has between $100$ mg and $200$ mg$.$