Monday, July 4, 2011

(Viva Voce) Chap 9 Exercise 9 Question {8}



***The starting the quality not so good***


Question 8)
 A man took 4 1/2 hours to drive 360 km from Singapore to Kuala Lumpur. He used 37.5 litres of petrol for the entire journey.
  1. Find his average speed.
total distance:360km
total time :4 1/2 
360km/4 1/2 = 80km/h 
so the average speed of the whole journey is 80km/h
  1. Find the petrol consumption rate in km/l
total distance : 360km
litres : 37.5 l
360 / 37.5l which is 9.6km/l
so the rate is 9.6km/l
  1. He drove an average speed of 110 km/h on a highway for 2 hours during his 
journey. Find his average speed for the remaining part of his journey.
remaining distance:360km ÷ (110km/h x 2h) = 140km


Choy Rui Zhi
remaining time : 4 1/2 - 2 h = 2 1/2 
140km/2 1/2 h = 56km/h 
so 56 km/ h is the average distance for the remaining part of the journey.

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