Sound Intensity Problem...check my work!?

Question

question: deep ultrasonic heating is used to promote healing of torn tendons. it is produced by applying ultrasonic sound over the affected area of the body. the sound transducer (generator) is circular with a radius of 1.8 cm, and it produces a sound intensity of 5.9 x 10^3 W/m^2. how much tiem is required for the transducer to emit 4800 J of sound energy?

My approach:
A = (3.14)r^2 = (3.14)(1.8^2) = 10.2 m^2
I = 5.9 x 10^3 W/m^2
E = 4800 J

I = P/A
5.9 x 10^3 = P/10.2
P= 60180 J/T

4800 J/ 60180 J/T = .0798 s <---final answer

Answer 1

Well, area is 10.2 cm^2, which is 10.2x10^-4 m^2.

The power crossing the 10.2cm^2 is:
P=5.9x10^3 W/m^2 * 10.2x10^-4 m^2 in Watts

Remember:
1Watt = 1Joule per second

time = Joules / Joules per second