The Area of a Circular Sun Spot Is Growing at a Rate

Multiple Choice

The area of a circular sun spot is growing at a rate of $600 \frac { \mathrm { km } ^ { 2 } } { \mathrm {~s} }$ . How fast is the radius growing at the instant when it equals 5,000 km Round your answer to three decimal places.

A) $\frac { \mathrm { km } } { \mathrm { s } }$
B) $0.019 \frac { \mathrm { km } } { \mathrm { s } }$
C) $0.038 \frac { \mathrm { km } } { \mathrm { s } }$
D) $8.333 \frac { \mathrm { km } } { \mathrm { s } }$
E) $0.060 \frac { \mathrm { km } } { \mathrm { s } }$