Most of your problems post unauthorized when linked.
The last one
Volume of the Cooler
Is solved by adding the volume of a rectangular prism (Vp=h*w*d) to that of half of the cylinder (Vc=1/2*pi*(w/2)^2*d) where h is height of the prism, w is the width of the prism and d is depth of the prism.
Rap