### (Viva Voce) Chap 9 Exercise 9 Question 10

Qn 10 a) Distance already travelled = 54km/h x 2/3h = 36km
Remaining distance = 120km - 36km = 84km
Remaining time = 2h - 2/3hr = 1 1/3h
Average speed = 84km ÷ 1 1/3h = 63km/h

b) i) average speed = 120km ÷ 2 1/6h = 55 1/3km/h
ii) Total distance = 120km + 120km = 240km
Total time = 2h + 2 1/6h = 4 1/6h
Average speed = 240km ÷ 4 1/6h = 57 3/5km/h OR 57.6km/h

1. (a)
1st step : 2/3 looks like 2/5. Never explain how u convert from 40 min to 2/5
3rd step: Never explain how u get 2/3 hour
4th step: You said 64km/h but the paper write is 63km/h

(b)
(i) Never explain how you get 2 1/6h
(ii) Again, never explain how you get 2 1/6h

Presentation: 1
Mathematical terms: 1
Explanation of working/solution : 1
Understanding of concepts: 2
Accuracy of answer: 2
Total: 7

2. Mathematical Terms [0] (Not much terms used)
Explanation of Solution [3]
Understanding of Concepts [2]
Accuracy of Answers [2]
Presentation [2]

Total: 9
G-O-O-D-J-O-B

3. @ Jia Qi : When you mean by explaining, does it mean I have to explain the workings?

4. 1. The approach to solve (a) is clearly explained.

2. The explanation to all the part are very clear.

3. Read "k""m" as kilometres; also write "hr" as "h".