Use the image to answer the question.

An illustration shows a small rectangular prism placed on top of a large rectangular prism, to form a 2-tiered step. The edges that are not visible are marked with dashed lines. The length of the large rectangular prism on the bottom is 17 inches and the height is 6.5 inches. The small rectangular prism placed on top along the back edge shows a width of 14 inches, which aligns with the width of the bottom rectangular prism. The total height of both rectangles is 13 inches overall. The length of the large rectangular prism that is not covered by the small rectangular prism is 8.5 inches.

Find the surface area of the two-tiered steps.

(1 point)
Responses

1,409.5 in.2
1,409.5 in. squared

879 in.2
879 in. squared

2,320.5 in.2
2,320.5 in. squared

1,171.5 in.2

1 answer

To find the total surface area of the two-tiered rectangular prisms, we will calculate the surface area of each prism separately and then combine the results.

Step 1: Calculate the surface area of the large rectangular prism.

Dimensions of the large rectangular prism:

  • Length: 17 inches
  • Width: 14 inches (since it matches the small prism's width)
  • Height: 6.5 inches

Surface area formula for a rectangular prism: \[ \text{Surface Area} = 2(lw + lh + wh) \]

Calculating each area:

  • \(lw = 17 \times 14 = 238 , \text{in}^2\)
  • \(lh = 17 \times 6.5 = 110.5 , \text{in}^2\)
  • \(wh = 14 \times 6.5 = 91 , \text{in}^2\)

Now plug these into the surface area formula: \[ \text{Surface Area} = 2(238 + 110.5 + 91) = 2(439.5) = 879 , \text{in}^2 \]

Step 2: Calculate the surface area of the small rectangular prism.

Dimensions of the small rectangular prism:

  • Length: 8.5 inches (as given)
  • Width: 14 inches
  • Height: 6.5 inches (the height top level)

Surface area for the small rectangular prism: \[ \text{Surface Area} = 2(lw + lh + wh) \]

Calculating each area:

  • \(lw = 8.5 \times 14 = 119 , \text{in}^2\)
  • \(lh = 8.5 \times 6.5 = 55.25 , \text{in}^2\)
  • \(wh = 14 \times 6.5 = 91 , \text{in}^2\)

Now plug these values into the surface area formula: \[ \text{Surface Area} = 2(119 + 55.25 + 91) = 2(265.25) = 530.5 , \text{in}^2 \]

Step 3: Combine the surface area of both prisms and subtract the area of the overlapping face.

The two prisms share a face area from the top of the larger prism that is beneath the smaller prism, which needs to be subtracted. The area of that face is:

  • Area of shared face: \(17 \times 14 = 238 , \text{in}^2\)

Final Calculation:

\[ \text{Total Surface Area} = \text{Surface Area (large)} + \text{Surface Area (small)} - \text{Area of shared face} \] \[ \text{Total Surface Area} = 879 + 530.5 - 238 = 1171.5 , \text{in}^2 \]

Thus, the total surface area of the two-tiered step is: \[ \boxed{1,171.5 , \text{in}^2} \]