## College Algebra 7th Edition

$s=5.33$ mi/h
Since $F$ varies jointly with $A$ and the square of $s$, we have: $F=kAs^{2}$ We are given: $F=220$ and $A=40$ and $s=5$, so we have: $220=k*40*5^2$ $220=1000k$ $k=220/1000=0.22$ Therefore: $F=0.22As^2$ Now we plug in $A=28$ and $F=175$ to find $s$: $175=0.220*28*s^{2}$ $175=6.16s^2$ $28.409=s^{2}$ $s=\sqrt{28.4090}=5.33$ mi/h