AMP - Aviation Maintenance Technician Powerplant Practice Exam

The volume of a cylinder equals 70 cubic inches when the piston is at bottom center. When the piston is at the top of the cylinder, the volume equals 10 cubic inches. What is the compression ratio?

1. 10:7

2. 10:1

3. 7:1

4. 7:10

The correct answer is: 7:1

The compression ratio can be calculated by dividing the larger volume by the smaller volume. In this scenario, the volume at top of the cylinder (10 cubic inches) should be divided by the volume at bottom center (70 cubic inches), resulting in a compression ratio of 71. This ratio indicates how much the volume changes from the largest capacity (top of the cylinder) to the smallest capacity (bottom center). Option A is incorrect because it incorrectly reverses the larger and smaller volumes. Option B is incorrect because it only has one value and does not represent a ratio. Option D is incorrect because it also reverses the larger and smaller volumes and has incorrect arithmetic.