Answer
The suspended mass is about 25kg
Work Step by Step
We can solve for the mass using the following formula:
$\Delta l=\frac{1}{E} \frac{F}{A}l_0$
$F=\Delta l *E*A*\frac{1}{l_0}$
$F=\Delta l *E_{steel}*A*\frac{1}{l_0}$
$F=0.00030m *200*10^9N/m^2*\pi (1/2*0.0023m)^2*\frac{1}{1m}$
$F=249N$
Now we can solve for the mass. Therefore;
$m=F/g$
$m=249N/(9.8m/s^2)$
$m\approx25kg$
The suspended mass is about 25kg.