Answer
$T = 473.6K$
Work Step by Step
For the fraction of electrons that greater than Fermi energy (f),
Use the equation $f = \frac{3kT}{2E_F}$
Here we solve or T. rearrange the equation
$T = \frac{2fE_F}{3K} $
For Lithium,
$E_F=4.70 eV$
$k = 8.62 \times 10^{-5} eV/K$
$f= 1.3\% = 0.013$
So
$T = \frac{2(0.013)(4.70 eV)}{3(8.62 \times 10^{-5} eV/K)} $
$T = \frac{0.1222 eV}{ 2.58 \times 10^{-4} eV/K)} $
$T = 473.6K$
