a 600 meter long train crosses a signal post in 20 seconds . how long will it take to cross a 3 kilometer long bridge , at the same speed ?
"s = 600 / 20 = 1530 mps s = 3600 / 30 = 120 sec = 2 min answer : b"
divide(divide(multiply(3, const_1000), speed(600, 20)), const_60)