document.write( "Question 30584: A train, an hour after starting, meets an accident which detains it one hour, after which it proceed at 3/5 of its former rate and arrives 3 hours late. But, had accident happened 80km farther, it would have been 1.5 hours late only. Find the original rate of the train and the length of the journey. \n" ); document.write( "
Algebra.Com's Answer #17291 by Fermat(136)![]() ![]() You can put this solution on YOUR website! Let v1 be the speed before the breakdown \n" ); document.write( "Let v2 be the speed after the breakdown \n" ); document.write( "v2 = (3/5)v1 \n" ); document.write( "============ \n" ); document.write( "The two journeys are identical except for the 80km part \n" ); document.write( "let s1 be the distance up to the 80 km part \n" ); document.write( "The difference in time taken between travelling the 80 km at v1 and at v2 is equal to the difference in time of the two late journeys - which difference is 1.5 hrs. \n" ); document.write( "In other words, it takes 1.5 hrs longer to travel 80 km when trvelling at v2 than it does when travelling at v1.\r \n" ); document.write( "\n" ); document.write( "time to travel 80 km at v1 = 80/v1 = t1 \n" ); document.write( "time to travel 80 km at v2 = 80/v2 = t2 \n" ); document.write( "t2 - t1 = 1.5 \n" ); document.write( "80/v2 - 80/v1 = 3/2 \n" ); document.write( "80(1/v2 - 1/v1) = 3/2 \n" ); document.write( "(80/v1)(5/3 - 1) = 3/2 \n" ); document.write( "(80/v1)(2/3) = 3/2 \n" ); document.write( "80/v1 = 9/4 \n" ); document.write( "v1 = 320/9 \n" ); document.write( "v1 = 35.5556 km/hr \n" ); document.write( "================== \n" ); document.write( "Let s2 be the distance travelled after the breakdown (in the first joiuurney), such that, \n" ); document.write( "s1 + s2 = L, where L is the overall journey distance travelled from the start to the final destination. \n" ); document.write( "Let T be the journey time without breakdowns. \n" ); document.write( "L = v1T \n" ); document.write( "======= \n" ); document.write( "In the first journey, excluding the 1hrs wait time, it takes 2hrs longer to travel the distance s2, at the speed v2, than at the speed v1 (normal/standard speed) \n" ); document.write( "t = s2/v1 \n" ); document.write( "t' = s2/v2 \n" ); document.write( "t' - t = 2 \n" ); document.write( "s2(1/v2 - 1/v1) = 2 \n" ); document.write( "(s2/v1)(5/3 - 1) = 2 \n" ); document.write( "s2/v1 = 2*3/2 = 3 \n" ); document.write( "s2 = 3v1 \n" ); document.write( "s2 = 106.6667 km \n" ); document.write( "================ \n" ); document.write( "The distance s1 is travelled in 1 hr (given) at speed v1 \n" ); document.write( "s1 = 35.5556*1 \n" ); document.write( "s1 = 35.5556 km \n" ); document.write( "=============== \n" ); document.write( "L = s1 + s2 \n" ); document.write( "L = 35.5556 + 106.6667 \n" ); document.write( "L = 142.2222 km \n" ); document.write( "=============== \n" ); document.write( " |