Answer
The new fundamental frequency is $1467~Hz$
Work Step by Step
We can find an expression for the original fundamental frequency:
$v = \sqrt{\frac{F}{\mu}}$
$\lambda~f = \sqrt{\frac{F}{\mu}}$
$f = \frac{1}{\lambda}~\sqrt{\frac{F}{\mu}}$
We can find the new fundamental frequency:
$v' = \sqrt{\frac{F'}{\mu}}$
$\lambda~f' = \sqrt{\frac{F'}{\mu}}$
$f' = \frac{1}{\lambda}~\sqrt{\frac{F'}{\mu}}$
$f' = \frac{1}{\lambda}~\sqrt{\frac{3.0~F}{\mu}}$
$f' = \sqrt{3.0}\times \frac{1}{\lambda}~\sqrt{\frac{F}{\mu}}$
$f' = \sqrt{3.0}\times f$
$f' = \sqrt{3.0}\times (847~Hz)$
$f' = 1467~Hz$
The new fundamental frequency is $1467~Hz$
