Question

Two trains leave a railway station at the same time. The first

train travels due west and the second train due north. The first

train travels 30km/hr faster than the second train. If after 30

minutes, they are 75km apart, find the average speed of each

train.​

Answer 1

Answer:

Let the average spped of the second train be x km/h.

Thus, the speed of the first train will be (x+5) km/h.

Distance travelled by the first train in two hours =2(x+5) km/h

Distance travelled by the second train in two hours =2x km/h

Using pythagoras theorem, we have

4x

2

+4(x+5)

2

=50

2

4x

2

+4x

2

+40x+100=2500

8x

2

+40x−2400=0

x

2

+5x−300=0

(x−15)(x+20)=0

x=15,−20

Ignore the negative value of the speed. We have,

Speed of the second train be 15 km/h.

Spped of the first train be (15+5)= 20 km/h.