The wheel of an engine of 300 cm in circumference makes 10 revolution in 6 seconds. what is the speed of the wheel (in km/h)?

Circumferences means one resolutions .
Therefore, distance covered in 10 resolutions =300 x 10 = 30 m
i.e., 30 meters in 6 seconds.
∴ Speed of wheel = 30/6 m/s = 5 m/s
∴ 5 m/s = 5 x (18/5) = 18 km/h