SOLUTION: pls. help me solve this problem. thank you. A passenger on the front train A observes that he passes the complete length of train B in 33 seconds when traveling in the same dire

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: pls. help me solve this problem. thank you. A passenger on the front train A observes that he passes the complete length of train B in 33 seconds when traveling in the same dire      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 351120: pls. help me solve this problem. thank you.
A passenger on the front train A observes that he passes the complete length of train B in 33 seconds when traveling in the same direction as B and in 3 seconds when traveling in the opposite direction. If B is 330 ft long, find the speed of the two trains.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A passenger on the front train A observes that he passes the complete length
of train B in 33 seconds when traveling in the same direction as B and in
3 seconds when traveling in the opposite direction.
If B is 330 ft long, find the speed of the two trains.
:
Let a = train A's speed, Let b = train B's speed
:
When traveling in the same direction, their relative speed is (a-b)
When traveling in opposite direction, their relative speed is (a+b)
:
We will be finding the speeds in ft/sec
:
Write two distance equations, dist = speed * time
33(a-b) = 330
33a - 33b = 330
simplify, divide by 33
a - b = 10
and
3(a+b) = 330
3a + 3b = 330
simplify, divide by 3
a + b = 110
:
Use elimination on these two equations
a - b = 10
a + b = 110
-----------------adding eliminates b, find a
2a = 120
a = 120%2F2
a = 60 ft/sec; speed of Train A; (that's %28%2860%2A3600%29%29%2F5280 = 40.9 mph
and
a + b = 110
60 + b = 110
b = 110 - 60
b = 50 ft/sec; speed of Train B: (that's %28%2850%2A3600%29%29%2F5280 = 34.1 mph