An octagonal prism has a length of 9.8cm.The area of its octagonal faces is 278.9cm2 and the sides of the octagons are each 7.6cm.Find its surface area correct to one decimal place.

To find the surface area of an octagonal prism, we need to add the area of the two octagonal faces to the area of the rectangular sides.

1. We are given that the area of the octagonal faces is 278.9 cm². Since there are two of these faces, their total area is 2 * 278.9 cm² = 557.8 cm².

2. To find the area of the rectangular sides, we need to know their width and height. The width is the length of the prism, which is given as 9.8 cm. The height is the same as the sides of the octagon, which is given as 7.6 cm. So, the area of one rectangular side is 9.8 cm * 7.6 cm = 74.48 cm².

3. An octagon has 8 sides, so there are 8 of these rectangles. Their total area is 8 * 74.48 cm² = 595.84 cm².

4. Finally, add the area of the octagonal faces to the area of the rectangular sides to find the total surface area: 557.8 cm² + 595.84 cm² = 1153.64 cm².

So, the surface area of the octagonal prism is approximately 1153.6 cm², correct to one decimal place.