a 600 meter long train crosses a signal post in 40 seconds . how long will it take to cross a 9 kilometer long bridge , at the same speed ?
"s = 600 / 40 = 15 mps s = 9000 / 15 = 600 sec = 10 min . answer : c"
divide(divide(multiply(9, const_1000), speed(600, 40)), const_60)