We know that
the area A of the circular cross section of the pipe is
A=pi*r²
D=20 cm------------- > r=D/2=20/2=10 cm
then
A=pi*10²=100*pi cm²
the answer is A=100*pi cm²
8 positions x 8 employees = 64 different ways
65:100 because there are 65 girls and then 65 girls + 35 boys = 100 total students
Answer:

Step-by-step explanation:
F(x)=1/3•4^x
f(3) = 1/3•4^3 = 64 / 3 = 