A metal box with a square base and vertical sides is to contain 1024 cm3. The material for the top and bottom costs Rs 5/cm2 and the material for the sides costs Rs 2.50/cm2 . Find the least cost of the box.
Given the volume of the box =1024 cm3
Let length of the side of square base be x cm and height of the box be y cm.
Thus for x = 8 , cost is minimum and the corresponding least cost of the box
