two trains are moving in opposite directions at 60 km / hr and 90 km / hr . their lengths are 1.10 km and 0.9 km respectively . the time taken by the slower train to cross the faster train in seconds is :
"relative speed = ( 60 + 90 ) km / hr = 150 x 5 / 18 = 120 / 3 m / sec distance covered = ( 1.10 + 0.9 ) km = 2 km = 2000 m . required time = 2000 x 3 / 125 = 48 sec . answer : c ."
subtract(divide(multiply(1.10, const_1000), divide(multiply(60, const_1000), const_3600)), divide(multiply(0.9, const_1000), divide(multiply(90, const_1000), const_3600)))