AAI ATC Junior Executive 2018 Shift 1 Paper

Ultrasonic pulse echo technique, a non-destructive ultrasonic testing, is employed for any possible flaw detection in a metallic bar of thikness 30 cm. If the arrival times of the ultrasonic pulses are 45 μs and 90 μs respectively, the distance of the flaw from one end of the steel bar at which the ultrasonic pulse initially enters the steel bar, will be: