# A balloon which always remains spherical is being inflated by pumping in gas at the rate of 900 cm3/sec. Find the rate at which the radius of the balloon is increasing when the radius of the balloon is 15 cm.

SHAIK AASIF AHAMED
7 years ago
Hello student,
Let r and V be varaibles for radius and volume respectively
(dv/dt)=900
$v=(4/3)\pi r^{3}$
(dv/dt)=4$\pi r^{2}$(dr/dt)
dr/dt=(dv/dt)/4$\pi r^{2}$=(900)/4$\pi$(15)(15)
so dr/dt=(1/$\pi$) cm/sec
Thanks and Regards
Shaik Aasif