document.write( "Question 162664: During the first part of a trip, a canoeist travels 69 miles at a certain speed. The canoeist travels 2 miles on the second part of the trip at a speed 5 mph slower. The total time for the trip is 3 hrs. What was the speed on each part of the trip? \n" ); document.write( "
Algebra.Com's Answer #119893 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! During the first part of a trip, a canoeist travels 69 miles at a certain speed. The canoeist travels 2 miles on the second part of the trip at a speed 5 mph slower. The total time for the trip is 3 hrs. What was the speed on each part of the trip? \n" ); document.write( "; \n" ); document.write( "Canoing that far in 3 hrs is a fantasy, but anyway: \n" ); document.write( ": \n" ); document.write( "Let s = speed on the 69 miles \n" ); document.write( "then \n" ); document.write( "(s-5) = speed on the last to miles of the trip \n" ); document.write( ": \n" ); document.write( "Write a time equation: Time = dist/speed \n" ); document.write( ": \n" ); document.write( "69 mi time + 2 mi time = 3 hrs \n" ); document.write( " \n" ); document.write( ": \n" ); document.write( "Multiply equation by s(s-5), results: \n" ); document.write( "69(s-5) + 2s = 3s(s-5) \n" ); document.write( "69s - 345 + 2s = 3s^2 - 15s \n" ); document.write( "71s - 345 = 3s^2 - 15s \n" ); document.write( "0 = 3s^2 - 15s = 71s + 345 \n" ); document.write( "A quadratic equation: \n" ); document.write( "3s^2 - 86s + 345 = 0 \n" ); document.write( "Use the quadratic formula to solve this \n" ); document.write( "The solution that makes sense is s ~ 23.84 mph for the 1st 69mi \n" ); document.write( "and \n" ); document.write( "23.84 - 5 = 18.84 mph for the last two mi \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Check solution by finding the times at each speed \n" ); document.write( "69/23.84 = 2.89 hrs \n" ); document.write( "2/18.84 = .106 hr \n" ); document.write( "---------------- \n" ); document.write( "total time 2.996 ~ 3 hrs \n" ); document.write( ": \n" ); document.write( "I suspect there may be a typo in this as written here, but the method should \n" ); document.write( "help you. \n" ); document.write( " |