The Student Room Group

Diffrentiation Problem C2

Finding di one tuff any one got any ideas

A pencil holder is in the shape of an open circular cylinder of radius r cm and height h cm. The surface area of the cylinder (including the base) is 250 cm2.

Show that the volume, V , of the cylinder is given by V = 125r  .

(b) Use calculus to find the value of r for which V has a stationary value.

(c)Prove that the value of r you found in part (b) gives a maximum value for V.

(d) Calculate, to the nearest cm3, the maximum volume of the pencil holder.
Reply 1
9. A pencil holder is in the shape of an open circular cylinder of radius r cm and height h cm. The surface area of the cylinder (including the base) is 250 cm2.
(a)Show that the volume, V , of the cylinder is given by V = 125r - (PIE R^3 /2)

(b)Use calculus to find the value of r for which V has a stationary value.

(c)Prove that the value of r you found in part (b) gives a maximum value for V.
(d)Calculate, to the nearest cm3, the maximum volume of the pencil holder
Reply 2
I jus worked it out got same answer thanks great help

Thanks