Can someone help me solve this? I'm supposed to calculate the median value of resistive force the steel plate exerts on the bullet when it ricochets. I've tried the following approach, but can't get nowhere near the correct solution:

$\frac{1}{2}m(v_a)^2-\frac{1}{2}m(v_b)^2=\Delta KE=W=F*d$

$F=\frac{W=\Delta KE}{d}$

Any ideas on what I'm doing wrong? I get $22000N$, but the correct solution is $9.5*10^7N$.