# Thread: primary 6 problem sum

1. ## primary 6 problem sum

Belle was travelling in the MRT. She was seated at the last seat of the last coach.During the journey,she noted the time on her watch was 12.18 P.M when the train just entered an underground tunnel.The moment she exited from the tunnel,the time was 12.23 P.M.Given that the train travelled at an average speed of 18 km/h and that the tunnel is 1350m long,find the length of the train in metres.

2. Distance = Rate * Time

What else do you need?

Rule #1 - Name Stuff.
Question #1 - Name what?
Answer #1 - What does it want? Name that.

L = Length of train in metres.

3. Originally Posted by mytan1963
Belle was travelling in the MRT. She was seated at the last seat of the last coach.During the journey,she noted the time on her watch was 12.18 P.M when the train just entered an underground tunnel.The moment she exited from the tunnel,the time was 12.23 P.M.Given that the train travelled at an average speed of 18 km/h and that the tunnel is 1350m long,find the length of the train in metres.
Notice:$\displaystyle 18\frac{km}{h} =5\frac{metres}{second}$
$\displaystyle time=5min=5\cdot 60sec=300sec$

$\displaystyle (length of the tunnel)+(length of the train)=speed\cdot time$
$\displaystyle (length of the train)=speed\cdot time - (length of the tunnel)$
$\displaystyle (length of the train)=300sec\cdot 5\frac{metres}{second} - 1350m=1500m-1350m=150m$

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