Question 1198829
{{{A(x)=pi*x^2}}}


{{{Average=(A(b)-A(a))/(b-a)}}}

where
{{{a=4}}}
{{{b=7}}}


find {{{A(a)}}} and {{{A(b)}}}

{{{A(4)=pi*4^2}}}

{{{A(4)=16pi}}}

{{{A(7)=pi*7^2}}}

{{{A(7)=49pi}}}

then

{{{Average=(49pi-16pi)/(7-4)}}}

{{{Average=(33pi)/3}}}

{{{Average=11pi}}}