Class 4    Math    Time and Distance

#### Calculate Train travel time based on few conditions

Question: Suppose a train runs at a speed of 40 kilometers in 1 hour, it stops at four stops for 4 minutes each after every 15 kilometers. How long it will take to travel 60 kilometers ?

Answer: To solve this problem, let us first calculate the total time the train will take to cover 60 kilometers. It needs to travel 60 kilometers and in one hour it travels 40 kilometers. So there are additional 20 (60 kilometers − 40 kilometers) kilometers the train needs to cover.

Let us write a simple equation to get the time taken by train to cover 20 kilometers:

40 kilometers in 1 hours; or; 20 + 20 Kilometers in 30 + 30 Minutes.
Hence, the train travels 20 kilometers in 30 minutes.

Now write another equation to calculate time take by the train to cover 60 kilometers:

40 kilometers in 1 hour;
so, 40 + 20 kilometers in 1 hour 30 minutes;
Hence, 60 kilometers in 1.5 hours or 1 hour 30 minutes.

Second part of the question is that train stops for 4 minutes after every 15 kilometers. Let us calculate total number of stops in 60 kilometers. This will be calculated by dividing total distance by 15.

So, total number of stops = 60 kilometers ÷ 15 kilometers = 4

This means that train will stop 4 times to cover 60 kilometers. One thing here to notice that after third stop, when the train runs for another 15 kilometers, then it completes its journey and there is no further move, so no need to count last stop as a valid stop point while calculating the time. Let us understand this by the diagram below:

As you can see that after 3rd stop, the train finally stops after covering 15 kilometers, so we are not considering last stop as 4th stop.

As the train stays for 4 minutes at one stop, so at three stop it will stay for: 3 stops x 4 minutes = 12 minutes

So, total travelling time = 1 hour 30 minutes + 12 minutes
= 1 hour 42 minutes (answer)