### 20110630 Chapter 9: Concluding Activity - Viva voce (a Practice)

Each member in the class has been assigned a number: #1, #2, #3, #4 or #5

You have been assigned to attempt the question your number has been assigned to:

Revision Exercise 9 (page 21-22_
Question 2 - attempted by those who have been assigned #1
Question 4 - attempted by those who have been assigned #2
Question 6 - attempted by those who have been assigned #3
Question 8 - attempted by those who have been assigned #4
Question 10 - attempted by those who have been assigned #5

You shall do the following:
1. Attempt the question in your notebook - work out the solution clearly
2. Using Quicktime Player or PhotoBooth, record your explanation of the solution as a video clip.
3. You may upload your video clip into Youtube before embedding it in a Post in the Maths Blog.
4. In the Maths blog
• Title: (Viva Voce) Chap 9 Exercise 9 Question {2, 4, 6, 8 or 10}
• Embed the video clip
• You may include a 'brief' write-up of the steps/ solutions
5. Complete the posting before the next lesson. We will discuss the rubric and give peer feedback in the next lesson.
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Question 2:
Car X travels 60 km in 45 minutes. Car Y travels 72 km in 1 h 20 min. Find
(a) The average speed of car X
(b) The average speed of car Y
(c) The ratio of average speeds of cars X and Y

Question 4:
Alcohol and water are mixed in the ratio 1:4 by volume. If the volume of the solution is 600cm^3
(a) Find the volume of alcohol in the solution
(b) Find the volume of water in the solution
(c) how much alcohol must be added to the solution so that the ratio of alcohol to water in the solution becomes 1:3 by volume?

Question 6:
(a) Simplify each of the following ratios
(i) a : b = 1 1/2 : 2 2/5 (ii) b : c = 0.105 : 0.350
(b) Find the ratio a : b : c using the data in (a)
(c) Alan, Bob and Cathy share \$500 in the ratio a : b : c found in (b). Find Alan's share correct to 2 decimal places.

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.
(a) Find his average speed.
(b) Find the petrol consumption rate in km/l
(c) 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.

Question 10:
Towns P and Q are 120 km apart. Mr Tan drove from P to Q and was scheduled to reach Q after 2 hours. His average speed was 54 km/h for the first 40 minutes.
(a) What was his average speed for the remaining journey if he managed to arrive just on time?
(b) The time taken for his return journey is 2 hours and 10 minutes. Find his average speed for
(i) the return journey (ii) the whole trip