A weather balloon in the shape of a sphere is being inflated by a pump. The volume of the balloon is increasing at a constant rate of $$$600 \mathrm{~cm}^{3}$$$ per second. The balloon was empty at the start of pumping. Find the radius of the balloon after 30 seconds. ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................

Mathematics

IGCSE&ALevel

CAIE

Exam No：9709_s20_qp_12 Year：2020 Question No：3(a)

Answer:

Volume after $30 \mathrm{~s}=18000 \quad \frac{4}{3} \pi r^{3}=18000$
\[
r=16.3 \mathrm{~cm}
\]