Part a.
It is given in the question that, The area of the pattern can be expressed as
[tex] A(p) = \pi p^2 [/tex]
And
[tex] p(t)=5t [/tex]
So for A(p(t)), we have to substitute 5t for p in A(p), that is
[tex] A(P(t)) = \pi(5t)^2
\\
A(p(t)) =25 \pi t^2 [/tex]
Part b .
At t=2minutes,
[tex] A(p(2)) = 25 \pi(2^2) = 25 \pi(4) = 314 [/tex]
And that's the required area at t=2 minutes .