Answer
$5.1\times 10^4N/m^2$
Work Step by Step
We can find the Young's modulus for the muscle tissue as follows:
$Y=\frac{FL_{\circ}}{\Delta L A}$
We plug in the known values to obtain:
$Y=\frac{(25N)(0.24m)}{(0.025m)(47\times 10^{-4}m^2)}$
$Y=5.1\times 10^4N/m^2$