Question 1163170
<pre>

Instead of doing it for you, I'll do another one exactly like yours with the
numbers changed.  I'll do this one:
</pre>
A spherical balloon is decreasing its volume at a rate of 274.98 cm³/min.
Find the rate at which the radius is decreasing when the volume is 5027.23
cm³.
Round to 5 significant digits.
<pre>
{{{V = expr(4/3)pi*r^3}}}

{{{V = 4.188790205r^3}}}

When the volume is 5027.23 cm³, the radius is

{{{5027.23 = 4.188790205r^3}}}

{{{5027.23/4.188790205=r^3}}}

{{{1200.162757=r^3}}}

{{{root(3,1200.162757)=r}}}

{{{10.6270661=r}}}

Now go back to the formula, allowing r and V to vary.

{{{V = 4.188790205r^3}}}

{{{dV/dt=3*4.188790205r^2*expr(dr/dt)}}}

{{{dV/dt=12.56637062r^2*expr(dr/dt)}}}

Now substitute the values:

{{{274.98=12.56637062(10.6270661)^2*expr(dr/dt)}}}

{{{274.98=1419.177209*expr(dr/dt)}}}

{{{274.98/1419.177209=dr/dt}}}

{{{0.19376=dr/dt}}}

Answer for my problem: 0.19376 cm²/min

Now do yours.

Edwin</pre>