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Wednesday, December 13 2017 @ 11:56 PM CST
 Forum Index >  Test Paper Related >  Primary 6 Matters
 P6 Math RSS 2012 SA1
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By: acelow (offline)  Saturday, September 21 2013 @ 08:27 AM CDT (Read 563 times)  
acelow

The distance between Town A and Town B was 350km. A car left Town A for Town B at 1pm with an average speed of 70km/h. A lorry left Town B for Town A at 12 noon with average speed of 50km/h . Assuming that both car and lorry travelled at a constant speed throughout the journey, at what time would the car and the lorry be 20km apart after the 2 vehicles pass each other?


Pls help again
Thank You Smile

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By: echeewh (offline)  Saturday, September 21 2013 @ 08:02 PM CDT  
echeewh

Hey <acelow>,

Appreciate that you put in the <Answerkey> as well , whenever possible. Smile

Following is my worked solution:

d(AB ) = 350 km
sC = 70 km/h
sL = 50 km/h

At 1pm (13 00) the lorry (L) would have travelled 50km. Thus distance separating car (C) and L is 300 km.

In order for C and L to be 20 km apart after passing each other, distance separating them is 320 km. Thus ...

time taken = 320 ÷ (70 + 50)
= 320 ÷ 120
= 2 2/3 hrs
= 2 hrs 40 mins

time = 13 00 + 2 40 = 15 40 = 3.40pm

==========

Trust this helps.

Do let me know again if this is different from your <Answerkey> or if there's further clarification.

Cheers,
Edward

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