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### Question

A train running at 4km/h leaves a railway station 21 hours later than another train, and meets it in 7 hours. What is the speed of the other train?

**A**

1 km/h.

**B**

2 km/h.

**C**

4 km/h.

**D**

3 km/h.

**Soln.**

**Ans: a**

Let the speed of the train be v km/h. Distance travelled by this train in (7 + 21) hours = 28v km. Equating this to the distance travelled by the second train we get 28v = 4 × 7, which gives v = 1 km/h.