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

My Video :

Please wait for a while as it takes a long time to load.

http://www.youtube.com/watch?v=aGcYHNh1FW0

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Solution:

Average speed = Total Distance ÷ Total Time
=360km ÷4 1/2 h
= 80km/h

Petrol Consumption rate = Total Distance ÷ Total petrol
=  360 km ÷ 37litres
=  9.6 km/l

Average speed of remaining part of journey = Remaining Distance ÷ remaining time

Distance of highway = 110 km/h × 2h
= 220 km

Remaining distance = 360 km − 220 km
= 140 km
Remaining time  = 4 1/2 h − 2h
=2 1/2h

Average speed of remaining part of journey = 140km ÷ 2 1/2 h
= 56 km/h

#### 2 comments:

1. Presentation: (0)
Mathematical terms (0)
Explanation of working/ solution (2)
Understanding of concepts (1)
Accuracy of answer (2)

Comments: Cant hear any sound so it is like watching a still movie. Sorry, but i cant give the accurate scores...if there is no sound

Owen here also doing same qn

2. @owen: I'm able to hear the explanation :)

1. It's a good idea to start with the question to set the context.

2. The explanation for (a) is very clear.

3. For (b), you've articulated clearly how to find the consumption rate :)

4. You've explained clearly how to get the remaining distance. You've also pointed out what kind of information is missing, and made a comparison on the method to find the distance. Well done.

5. Notice you have this practice of highlighting the key information. Good :)

6. The visuals: Consider enlarging the font size.

7. There's background noise captured. For future recording, try to find a quieter place.