What is the average piston speed of a five cylinder low- speed engine with a bore of 29.5 inches (75 cm), a stroke of 63 inches (160 cm), and a rated speed of 123 RPM?

Correct Answer: Option B — 1291 ft/min (393 m/min)

Piston speed is calculated as two times stroke multiplied by RPM, divided by twelve. With a 63-inch stroke and 123 RPM, the formula (2 × 63 × 123) / 12 yields 1,291 feet per minute (393 meters per minute).