two trains are moving in opposite directions at 60 km / hr and 90 km / hr . their lengths are 1.15 km and 0.6 km respectively . the time taken by the slower train to cross the faster train in seconds is ?
": relative speed = 60 + 90 = 150 km / hr . = 150 * 5 / 18 = 125 / 3 m / sec . distance covered = 1.15 + 0.6 = 1.75 km = 1750 m . required time = 1750 * 3 / 125 = 42 sec . answer : a"
subtract(divide(multiply(1.15, const_1000), divide(multiply(60, const_1000), const_3600)), divide(multiply(0.6, const_1000), divide(multiply(90, const_1000), const_3600)))