Friday, September 10, 2010

Speed P6 2010 Rosyth P2 Q17

A tour bus which left Kuala Lumpur at 10.30 a.m. was scheduled to reach Singapore by 5 p.m. After travelling for 2 hours at its usual speed, the bus stopped for 30 minutes due to some problems. In order to reach Singapore punctually, the bus increased its speed by 8.5 km/h. Given that the bus took 4 hours to complete the rest of the journey, find the distance between Kuala Lumpur and Singapore.[5 marks][Answer given: 442 km]


10.30 am       2 h     ---> S + 8.5 km/h, 4 h        5 pm
       |-----------------|-------------------------------|
      K                30 min
                           stop

8.5 x 4 = 34 km     Distance covered by the increased speed in 4 h (1 pm to 5 pm)

1/2 h --> 34 km    Time lost (due to resting) and the distance it would have had travelled
1 h --> 1 x 2 x 34 = 68 km    Original speed 68 km/h

68 x 2 = 136 km

68 + 8.5 = 76.5 km/h

76.5 x 4 = 306 km

136 + 306 = 442 km

It was 442 km.

2 comments:

  1. Obs,
    May I know why 8.5 x 4? & 1/2h --> 34km?

    ReplyDelete
  2. I haved added comments in red. Hope they clear your doubts.

    ReplyDelete