Answer
$n=2$
Work Step by Step
For this calculation, digits that are not significant numbers will be underlined, and the numbers will
have up to 4 decimal places to avoid rounding off errors:
$-0.1875=0.2\underline{5}-\frac1{n^2}$
$\frac1{n^2}=0.4\underline{375}$
$n^2=2.\underline{2857}$
$n=1.\underline{5118}$
Rounding to one significant number $n=2$
