Answer
$d = 3.2~cm$
Work Step by Step
We can use this formula:
$d = (\frac{n_2}{n_1})~d'$
where $d$ is the actual distance and $d'$ is the apparent distance.
We can find the actual distance:
$d = (\frac{n_2}{n_1})~d'$
$d = (\frac{1.59}{1.00})~(2.0~cm)$
$d = 3.2~cm$
