The perimeter of a square chip is 160 mm. The width of a rectangular display is 80% of the side of this square chip. If the area of the rectangular display is 1920 mm2, what is its perimeter in mm?

Find the approximate volume and surface area of a sphere of radius 6 cm. (Use π = 227)

Ram has two spherical balls of radius 10.5 cm each and Meena has six spherical balls of radius 7 cm each. What is the total volume of the balls that Meena has?