(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

4 comments:

  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

    ReplyDelete
  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

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

    ReplyDelete
  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".

    ReplyDelete