Answer: a) 4 days, b) Maximized percent = 16.46.
Step-by-step explanation:
Since we have given that
[tex]p(t)=-t^2+8.1t+0.06[/tex]
We need to find the maximum percent and number of days before the percent is maximized.
So, first we derivative the above p(t), we get that
[tex]p'(t)=-2t+8.1[/tex]
Now, we will find the critical points :
[tex]p'(t)=0\\\\-2t+8.1=0\\\\-2t=-8.1\\\\t=\dfrac{-8.1}{-2}\\\\t=4.05[/tex]
So, we will check at t = -4.05, whether it gives maximum percent or not.
So, it becomes,
[tex]p''(t)=-2<0[/tex]
So, a) there would be 4 days before the percent is maximized.
b) maximum percent would be
[tex]p(4)=-(4)^2+8.1(4)+0.06=16.46[/tex]
Hence, a) 4 days, b) Maximized percent = 16.46.