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)

Average piston speed is calculated using the formula V = 2 × Stroke × RPM. With a 63-inch (5.25 ft) stroke and 123 RPM, the calculation yields 2 × 5.25 × 123 = 1291.5 feet per minute.