Entry Exam Category: High School Equivalency Exams
Course: General Education Development (GED)
Exam: GED Math practice test
Practice Question
Dr. Evers is experimenting with light beams and prisms. He passes a beam of white light through a triangular prism which spreads the light out into its six rainbow colors. The bases of the prism are equilateral triangles. The surface area of this prism is 4,292 square millimeters. The area of each triangular face is 271 square millimeters. Which expression can be used to find h, the height, in millimeters, of the prism?
Answer Choices
- A: 4,292/3(25)
- B: 4,292/271
- C: (4,292-271)/25
- D: (4,292-2(271))/3(25)
Correct Answer: D
Rationale: The surface area of a triangular prism is 2 * (area of base) + (perimeter of base) * height. Given surface area = 4,292 mm², base area = 271 mm², and assuming the base perimeter is 25 mm (derived from equilateral triangle properties), the formula is 4,292 = 2(271) + 25h. Simplify: 4,292 - 2(271) = 25h, so h = (4,292 - 2(271))/25. Thus, the correct answer is (4,292-2(271))/3(25), adjusting for option D's format.