The width is 10cm. The length is 2x the width, which is 2x10 = 20cm. The height is half th…e width which is 10/2 = 5cm. Thus the dimensions of the book are 10cm x 20cm x 5cm. To work out the volume you multiply these dimensions together: 10x20x5 = 1,000 Thus the volume of the book is 1,000cm3. 4 people found this useful.