Hey, can you check my working for this question please. :
"The volume of a sphere is increasing at a rate of 75cm^3/s. Find the rate at which the radius is increasing at the instant when the radius of the sphere is 15cm."
My working :
dv/dt = 75
v = 4/3*pi*r^3
dv/dr = 4*pi*r^2
dr/dt = dr/dv * dv/dt
Therefore dr/dt = 75/(4*pi*r^2)
When r = 15
dr/dt = 0.0265
Is this right? any comments will be appreciated. Thanks.
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- Thread Starter
- 20-06-2004 21:01
- 20-06-2004 21:08
looks right to me (but i've not checked things like your muliplication)
good luck tomorrow!