Q&A - PSLE Math
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lizawa:
Hi LizawaHi Tianzhu,
Your answer is correct. My son has tried this paper before. But I remembered our answer key did have the correct answer.
Lizawa
Thanks, appreciate it if you could share your solution. -
Large packet
c:s:t
= 1:2:3
Standard packet
c:s
4:5
Large packet contains 2x as many candies as standard packet.
No. of units (standard packet) = 9
no. of units (large packet) = 9 2 = 18
therefore, c:s:t = 3:6:9
(a) 1 standard + 1 large, c:s:t = 7:11:9
(b)
before eating : c:s:t = 7:11:9
after eating 21 candies, c:s:t = 2:3:3 = 6:9:9
No toffee candies are eaten
18u - 15u = 21
3u = 21
u =7
candies left = 247 = 168. -
Hi lizawa
Thank you for your fast response. -
Thank You for your time in helping to solve this problem.Trying to figure out without using Algebra.
http://farm3.static.flickr.com/2407/2673911274_a92537168a_o.jpg\"> -
hi tianzhu.
the area refers to the white space labeled A,B and C, or the area of the circle A, B, C ?
lizawa -
lizawa:
Hi lizawahi tianzhu.
the area refers to the white space labeled A,B and C, or the area of the circle A, B, C ?
lizawa
I believe it refers to the areas of circle A,B and C. -
Hi tianzhu,
my son said this type of question normally refers to unshaded part of A:B:C
Do you have the answer ?
Is it : 25:18:1 ? -
Solution
Total area of cirlces
(B+C) : A
= 4:5
= 24:30
1/6 of A shaded -> 1/6 * 30 = 5 units shaded
unshaded A -> 30 units - 5 units = 25 units
unshaded (B+C) -> 24 - 5 = 19 units
Can draw model here, to see clearer.
B has 5 units, C has 3 units. Size of units in B and C are different.
5 units of B + 3 units of C -> 24
1 unit of B + 1unit of C -> 5
3 units of B + 3 units of C ->15
2 units of B -> 24 - 15 = 9
unshaded B = 4 units of B -> 9 * 2 = 18
2 units of C -> 24 - 18 - 5 = 1
unshaded C = 2 units = 1
unshaded
A:B:C
= 25:18:1 -
Hi lizawa
Thanks
The answer listed in the worksheet is 20:15:1 -
[quote]The answer listed in the worksheet is 20:15:1
[/quote]then, in that case, it's asking for the total area of A : B:C
Extension to the above solution,
unshaded B = 18
total B = 22.5
unshaded C =1
total C = 1.5
A:B:C
30:22.5 : 1.5
= 60:45:3
= 20:15:1