two trains are moving in opposite directions at 60 km / hr and 90 km / hr . their lengths are 2.9 km and 1.6 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 = 2.9 + 1.6 = 4.5 km = 4500 m . required time = 4500 * 3 / 125 = 108 sec . answer : e"
subtract(divide(multiply(2.9, const_1000), divide(multiply(60, const_1000), const_3600)), divide(multiply(1.6, const_1000), divide(multiply(90, const_1000), const_3600)))