JEE Main & Advanced
Mathematics
Applications of Derivatives
Question Bank
Critical Thinking
question_answer
The volume of a spherical balloon is increasing at the rate of 40 cubic centrimetre per minute. The rate of change of the surface of the balloon at the instant when its radius is 8 centimetre, is [Roorkee 1983]
A)\[\frac{5}{2}\] sq cm/min
B)5 sq cm/min
C)10 sq cm/min
D)20 sq cm/min
Correct Answer:
C
Solution :
Here \[f'(x)=2x\log x+x\] and \[S=4\pi {{r}^{2}}\]