document.write( "Question 195507: Respected sir,\r
\n" );
document.write( "\n" );
document.write( "1] A train travelling 25km an hour leaves Delhi at 9 a.m. & another train travelling 35 km an hour starts at 2 p.m. in the same direction . how many km from Delhi are they together ?\r
\n" );
document.write( "\n" );
document.write( "2] Walking 3/4 of his usual rate,a man is 1 1/2 (one an half hour) hours too late.find his usual time.\r
\n" );
document.write( "\n" );
document.write( "plz sir solve my difficulty as soon as possible.\r
\n" );
document.write( "\n" );
document.write( "thank u. \n" );
document.write( "
Algebra.Com's Answer #146638 by ejazali_syed(7)![]() ![]() ![]() You can put this solution on YOUR website! 1)A train travelling 25km an hour leaves Delhi at 9 a.m. & another train travelling 35 km an hour starts at 2 p.m. in the same direction . how many km from Delhi are they together ? \r \n" ); document.write( "\n" ); document.write( "speed = distance/time => distance = speed *time\r \n" ); document.write( "\n" ); document.write( "d = 25*5 = 125 kms. i.e. by the time the second train starts travelling which is 5 hrs after the first one the first train has covered a distance of 125kms.\r \n" ); document.write( "\n" ); document.write( "for the first train => d1 = 25*t1; \n" ); document.write( "for the second train => d2 = 35*t2\r \n" ); document.write( "\n" ); document.write( "so the second train will catch the first train in t2 hrs.\r \n" ); document.write( "\n" ); document.write( " relation of t1 in terms of t2 => t1 = t2+5 (since train 1 has started moving 5 hrs before t2)\r \n" ); document.write( "\n" ); document.write( "we need the condition d1 = d2 => 25(t2+5) = 35(t2) \n" ); document.write( " 35t2-25t2 = 125 => t2 = 125/10 \r \n" ); document.write( "\n" ); document.write( " hence they will meet eachother after 12.5 hrs of train 2 leaving the station.\r \n" ); document.write( "\n" ); document.write( "i.e. 2.30 am \n" ); document.write( "------------------------------------------------ \n" ); document.write( "2)Walking 3/4 of his usual rate,a man is 1 1/2 (one an half hour) hours too late.find his usual time. \n" ); document.write( "plz sir solve my difficulty as soon as possible. \r \n" ); document.write( "\n" ); document.write( "same formula s = d/t --------- 1\r \n" ); document.write( "\n" ); document.write( "let s be the usual rate. d be the distance travelled in t hrs\r \n" ); document.write( "\n" ); document.write( "today he waliking at 3/4 of usual rate = 3s/4. and to cover the distance d it took 1.5 hrs more i.e. t+1.5\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "so 3s/4 = d/(t+1.5) ---------------2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "usual time t = ?\r \n" ); document.write( "\n" ); document.write( "from 1 d = st \n" ); document.write( "from 2 d = 3s(t+1.5)/4\r \n" ); document.write( "\n" ); document.write( "therefore st = s(3t+4.5)/4 ==> 4t = 3t +4.5 => t = 4.5 hrs is the usual time. \n" ); document.write( " |