### VIVA Voce Chapter 9 Exercise 9 Question 6

6. (a) Simplify each of the following ratios.
1. a : b = 1½ : 2⅖
1. b : c =  0.105 : 0.350
1. 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.
1. i)
A : b
=1 1/2 : 2 2/5
=1 5/10 : 2 4/10
=15/10 : 24/10
=15 : 24
=5 : 8
ii)
B:c
=0.105 : 0.350
=21/100 : 7/20
=21/100 : 35/100
=21 : 35
=3 : 5

(b)
A : b : c
=5: 8
=     3 : 5
_________
=15: 24: 40

(c)
15u+24u+40u=79u
79u-->\$500
1u-->\$500÷79=\$6.33 (2d.p.)
15u-->\$6.33 x 15=\$94.95

1. This comment has been removed by the author.

2. mathematical terms [1]
explanation of working/solution must be clear [3]
understanding of concept [1]
- converted wrongly
accuracy of answers [1]
- for b : c when converted into fraction it is 21/200 : 35/100 so a:b:c should be 15:24:80 instead.
presentation [1]
- you should type the working while you speak.

3. Mathematical terms [1]
Explanation on working [3]
Understanding of concept [1]
- working mistake
accuracy of answer [1]
- converted wrongly
Presentation [2]
- it is clear .

4. Mathematical terms (1)
explanation of working (3)
understanding of concept (1)
like Dys, you converted it wrongly 3 : 10 to 3: 5
accuracy of answer (1)
6a)(i) and 6b) is wrong
Presentation (2)
Good!!! x)

5. 1. You have articulated the reason to convert the numbers, i.e. to make the comparison easier. You have also explained how to go about converting, i.e. by changing the denominator of both fractions to the same. Good :)

2. The explanation of the conversation is very clear. Very good.

3. For (c), instead of saying "b is a constant value", it would be better to say "b is common element in both ratios".

4. You have clearly explained using LCM to express the 2 ratios such that the common element is represented by the same number of units so that we can make comparison. Good choice of words in the explanation. Good :)

5. Nevertheless, there's a computational error in (b) which affected the answer in part (c).

6. Ignoring the acccuracy, the explanation to part (c) is very clear :)

7. It's an interesting attempt that you tried to explain while typing the text. Not sure if it takes up too much time or not? If it does, you may want to consider having the steps keyed in/ written first :)

8. To improve the visual further, increase the font size. Else, the viewer would have difficulty to see.

6. Ms Loh,

Thank you for your feedback, I'll try to improve on those areas.