Graphical Approach to solve multi-stepproblems

T. T. Liang, Brain Maths, Vol. 2, problem 44

The railway distance between town X and Y is 680 km. A train traveling at 75 km/hr leaves town X heading for town Y. At the same time, a second train traveling at 95 km/hr leaves town Y heading for town X. How far apart are the trains 1 hour before they meet?

Graphical Approach to solve multi-stepproblems

The railway distance between town X and Y is 680 km. A train traveling at 75 km/hr leaves town X heading for town Y. At the same time, a second train traveling at 95 km/hr leaves town Y heading for town X. How far apart are the trains 1 hour before they meet?

X

Y

680 km

75 km/hr

95 km/hr

Graphical Approach to solve multi-stepproblems

How far apart are the trains 1 hour before they meet?

?

Graphical Approach to solve multi-stepproblems

Distance: 680 kmSpeed: Train leaving town X: 75 km/hr Train leaving town Y: 95 km/hr

Determine 1) When the trains meet,2) Where they are 1 hr before they meet.

Graphical Approach to solve multi-stepproblems

Distance: 680 kmSpeed: Train leaving town X: 75 km/hr Train leaving town Y: 95 km/hr

680 km

Graphical Approach to solve multi-stepproblems

Distance: 680 kmSpeed: Train leaving town X: 75 km/hr Train leaving town Y: 95 km/hr

T: Time when the trains meet

680 km

75 km/hr T 95 km/hr T

Graphical Approach to solve multi-stepproblems

680 km

75 km/hr T 95 km/hr T

Graphical Approach to solve multi-stepproblems

680 km

75 km/hr T 95 km/hr T

680 km = 170 km/hr T

Trains meet 4 hrs after they depart.

T = 4 hrs

Graphical Approach to solve multi-stepproblems

680 km

75 km/hr T 95 km/hr T

Trains meet 4 hrs after they depart.

What is the distance between the trains1 hour before they meet?

?75 km 75 km 75 km 95 km95 km95 km

3 hours 3 hours

Graphical Approach to solve multi-stepproblems

680 km

75 km/hr T 95 km/hr T

What is the distance between the trains1 hour before they meet?

75 km 75 km 75 km 95 km95 km95 km ? 170 km3 hours 3 hours

Graphical Approach to solve multi-stepproblems

680 km

75 km/hr T 95 km/hr T

What is the distance between the trains1 hour before they meet?

75 km 75 km 75 km 95 km95 km95 km 170 km

170 km