## Sunday, August 21, 2011

### Answers - Maths Practice Paper 7a

1.   3
2.   2
3.   2
4.   1
5.   2

6.   3
7.   2
8.   2
9.   4
10.  1

11.   3
12.   2
13.   2
14.   1
15.   4

16.  428.15
17.  0.25 or 1/4
18.  5
19.  1/10
20.  (3p +  12)  or  3(p + 4)

21.  2.25 or 2 1/4
22.  45°
23.  SE / South-East
24.  180
25.  (3p - 4)

26.
3 units ® \$8.40
4 units ® \$ 11.20
\$11.20  +  \$5  =  \$16.20                   [M1], [A1]

27. 28

28.  100 – 81  = 19                                   [M1]
19/ 100  =  19%                                [A1]

29.
ÐDAB  =  120°   ÐYAB  =  140°
ÐAYZ  =  180° – 140°              [M1]
=  40°                 [A1] or [A2]

30.

10%     ®     8
210%   ®    168                    [M1], [A1]

1. Hi - Could someone pls post the working for Q28 - I am unable to get the answer. Thanks in advance.

2. Isn't this the document you sent us? How come it's here?

P.S. The symbols are a bit weird. It's that lousy ASCII coding again.

3. Symbol Conversion Guide:

® = right arrow sign (if this doesn't come up weird this time, it's )

Ð = Angle sign ()

[number]/[number] (e.g. 19/100) = numerator/denominator

4. How to get the answer for qn 28? Could someone explain please?

5. Hi Mdm Toh - the first anonymous comment re Q28 - was from me - Devesh's mother. Second one was not me. Was instructed by Devesh to own up to the comment :-). But seriously - we did not get the answer as the pattern does not go up exponentially - which would be required for pattern 9 to use 81% of the chips. So obviously I am missing something.

Mrs Logendran

6. I think 81 was from 9 times 9. I am not too sure as well...

7. pattern 5-5×2=10
10-1=9
pattern6-6×2=12
12-1=11
pattern7-7×2=14
14-1=13
Pattern 8-8×2=16
16-1=15
Pattern 9-9×2=18
18-1=17
(Pattern 1 to 9)1+3+5+7+9+11+13+15+17=81
100-81=19

(19÷100)×(100÷1)=19%

8. O no. In a prime example of careless mistakes - I failed to realise that it is cumulative use of chips. Got the pattern right - but did not add them all up. Lesson in how it is important to read the question properly! Thanks to whoever posted the solution.
Mrs Logendran

9. I got the answer wrong too..So, thanks to whoever helped me understand the question.
Bhairavi Buddhamurthy