Entry Exam Category: High School Equivalency Exams
Course: General Education Development (GED)
Exam: GED Math practice test
Practice Question
A diver jumps from a platform. The height, h meters, the diver is above the water t seconds after jumping is represented by h = -16t^2 + 16t + 6.5. To the near hundredth of a second, how many seconds after jumping is the diver 2.5 meters above the water?
Answer Choices
- A: 2.79
- B: 1.32
- C: 2.83
- D: 1.21
Correct Answer: D
Rationale: Solve h = -16t^2 + 16t + 6.5 = 2.5. Simplify: -16t^2 + 16t + 4 = 0. Divide by -4: 4t^2 - 4t - 1 = 0. Use quadratic formula: t = [4 ± ˆš(16 + 16)]/8 = [4 ± ˆš32]/8 = [4 ± 4ˆš2]/8 = [1 ± ˆš2]/2. Approximate: t ? 1.207 ? 1.21 seconds (positive root). Thus, the correct answer is 1.21.