A company produces magnetic picture frames by cutting shapes from plastic coated magnetic sheet as illustrated below. The darker blue portions represent the picture frames; the diagram is not drawn to scale. Six frames with external dimensions 9 cm by 9 cm can be cut from a 21 cm by 31 cm sheet, with a 1 cm gap between frames. Calculate the material utilisation for this set of six frames if the width of the rim of the frames (shaded dark blue on the diagram) is 2.0 cm. You can assume that the magnetic sheet has uniform thickness and density, so the material utilisation can be calculated directly from a ratio of areas, since area will be proportional to mass. Give your answer to 2 decimal places. Material utilisation: