Length of Pendulum Increading by Factor of 9 Increaeses Period By 1 Second - Find Length and Period

If the length of a simple pendulum increases by a factor of 9, the period increases from
$t$
to
$t+1$
. What is
$T$
and what is the length of the pendulum?
The period of a pendulum is given by
$T= 2 \pi \sqrt{ \frac{l}{g}}$
.
Originally
$t= 2 \pi \sqrt{ \frac{L}{g}}$
, and then
$t+1= 2 \pi \sqrt{ \frac{9L}{g}}$
.
Dividing the second equation by the first gives
$\frac{t+1}{t}= \sqrt{9}=3$
.
Then
$t+1=3t \rightarrow 1=2t \rightarrow t=0.5$
.
Then
$T= 2 \pi \sqrt{\frac{l}{g}} \rightarrow l = \frac{gT^2}{4 \pi^2} =\frac{9.8 \times 0.5^2}{39.47}=0.062$
m to 3 decimal places.