Mensuration (Pyramid, Cones and Spheres) - Volume and Surface Area of Composite Solids

A wooden support is made from a solid cuboid measuring \(30\) cm long, \(20\) cm wide and \(12\) cm high.
A straight groove with a semicircular cross-section of diameter \(12\) cm is cut along the entire \(30\) cm length. The groove opens at both ends. Its end view is shown below (not drawn to scale).

Length perpendicular to this end view: \(30\) cm

1. Calculate the volume of wood remaining.

   [3]

2. Every exposed surface is varnished, including the curved surface inside the groove, both ends and the underside. Calculate the area to be varnished.

   [4]

Give both answers to \(3\) significant figures.