# The half life of Chemical Q is 12 days. If you started your experiment with 42 grams, how much would be left in 73 days?

Jul 30, 2016

$= 0.656$ grams

#### Explanation:

During $73$ days chemical Q will decay $\frac{73}{12} =$ at least $6$ times
And it will decay by half each time.
So we can write
$42 {\left(1 - 0.5\right)}^{6}$
$= 42 {\left(0.5\right)}^{6}$
$= 42 \left(0.015625\right)$
$= 0.656$ grams will be left after 73 days