Question

Please help

The problem below is solved incorrectly.



Part A: Find the mistake in the work/answer and explain what the mistake is.

Part B: Find the correct answer.

Answer 1

The given figure is a right triangular prism, with 2 parallel and congruent triangular faces and 3 rectangular faces.

The triangular faces have sides 13 ft, 13ft and 24 ft and the height of 5 ft.

Two of the rectangular faces are 13 ft x 30 ft and the remaining face is 24 ft x 30 ft.

Surface area is the sum of areas of all 5 faces.

Area formula for triangle is A = bh/2 and for rectangle is A = ab.

Let's verify the steps of calculation.

Part A

Step 1

• 13 x 30 = 390, right
• 390 x 2 = 780, right

This is right

Step 2

• 30 x 24 = 720, right
• 720 x 2 = 1440, wrong as there is only one face of same dimensions

This is wrong

Step 3

• 24 x 5 x 0.5 = 60, right
• 60 x 2 = 120, right

This is right

Step 4

• 780 + 1440 + 120 = 2340 sq ft, this is wrong because of wrong step 2

Part B

Correction in step 2, it should be 720 but not 1440.

Correction in last step, the sum:

• 780 + 720 + 120 = 1620 sq ft