Q&A - PSLE Math

Academic support for Primary 6 and PSLE
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tianzhu
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Re: Q&A - PSLE Math

Post by tianzhu » Wed Mar 30, 2016 7:01 am

SOS mum wrote:Hi, ps help. Many tks and God Bless:)

In a swimming club, the ratio of the number of girls to the number of boys was 5:3. After 3 girls and 5 boys joined the club, the ratio became 7:5. How many girls were there in the club at first?
Hi SOS mum

Good Morning.

You may wish to take a look a solution for a similar question.

Hope this helps.

Best wishes.

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tianzhu
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Re: Q&A - PSLE Math

Post by tianzhu » Wed Mar 30, 2016 7:45 am

SOS mum wrote:Hi, ps help. Many tks and God Bless:)

In a swimming club, the ratio of the number of girls to the number of boys was 5:3. After 3 girls and 5 boys joined the club, the ratio became 7:5. How many girls were there in the club at first?
Hi SOS mum

Good Morning.

I've managed to find another old similar solution, hope you'll find it useful.

Once students become more familiar, they may just consolidate the information into one table.

Best wishes.

Image

Ender
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Re: Q&A - PSLE Math

Post by Ender » Wed Mar 30, 2016 8:16 am

SOS mum wrote:Ps help the following qns. Many tks and God Bless:)

(1) The total number of game cards that Fandi and Geetha had was the same as the number that Eugene had. The total number of game cards that Eugene and Geetha had was 5 times the number that Fandi had.
(a) What was the ratio of the number of game cards that Eugene had to the number of game cards that Geetha had to the number of game cards that Fandi had?
(b) Eugene had 118 game cards more than Fandi. How many game cards did the 3 children have altogether?
E+G = 5F --(1)
Therefore total of E+G+F = 5F + F = 6F

EG: F
5 : 1 --> Let F be 1u, and E+G be 5u

We know F+G =E, (Given in the question)
1u + G = E

Substitute E into eqn (1)
(1u+G) + G = 5u
1u +2G = 5u
2G = 4u
G = 2u

From eqn(1), E= 5u-G
E= 5u-2u=3u

Ratio E : G :F => 3 : 2 : 1

b) 3u - 1u = 118
2u= 118
u=59

Altogether there are 6u = 6(59) = 354

Ender
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Re: Q&A - PSLE Math

Post by Ender » Wed Mar 30, 2016 8:40 am

SOS mum wrote:Ps help the following qns. Many tks and God Bless:)

(2) Jason and Ricky have 276 marbles altogether. 1/4 of Jason's marbles is 15 more than 1/5 of Ricky's marbles.
(a) How many marbles does each boy have?
(b) Find the ratio of the number of Ricky's marbles to the number of Jason's marbles.
If Rick's has 5u, 1/4 of Jason would be u+15. Which makes Jason total to be 4u +60

Total = 276 = 5u +4u +60
276 = 9u + 60
216 = 9u
u = 24

Jason = 5u = 120
Ricky = 4u + 60 = 156

b) R : J => 156 : 120 => 13: 10

SOS mum
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Re: Q&A - PSLE Math

Post by SOS mum » Wed Mar 30, 2016 8:42 am

numeric wrote:
SOS mum wrote: The ratio of the number of muffins to the number of pies in a bakery was 4:1. After another 63 muffins and 46 pies were baked, the ratio became 3:1. How many muffins and pies were there in the bakery at first?
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Tks. Numeric!


SOS mum
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Re: Q&A - PSLE Math

Post by SOS mum » Wed Mar 30, 2016 8:44 am

tianzhu wrote:
SOS mum wrote:Hi, ps help. Many tks and God Bless:)

In a swimming club, the ratio of the number of girls to the number of boys was 5:3. After 3 girls and 5 boys joined the club, the ratio became 7:5. How many girls were there in the club at first?
Hi SOS mum

Good Morning.

I've managed to find another old similar solution, hope you'll find it useful.

Once students become more familiar, they may just consolidate the information into one table.

Best wishes.

Image
Tks. Tianzhu for the 2 examples!

Ender
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Re: Q&A - PSLE Math

Post by Ender » Wed Mar 30, 2016 8:45 am

SOS mum wrote:Ps help the following qns. Many tks and God Bless:)

(3) A group of people visited a museum. The admission tickets were $2 for an adult and $0.50 for a child. If the ratio of the number of people to the amount of money collected (in dollars) for admission was 7:8, what fraction of the people were adults?
Let number of Adult be A, and children be C
Collection from adult = 2A
Collection from children = C/2

2A + C/2 = 8u ---(1)
A + C = 7u ------(2)

Mulitiply 2 to eqn (1) 4A + C = 16u --(3)

(3) - (2)
3A = 9u
A = 3u

Total is 7u, therefore fraction of adult => 3/7 of total audience.

SOS mum
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Re: Q&A - PSLE Math

Post by SOS mum » Wed Mar 30, 2016 8:45 am

Ender wrote:
SOS mum wrote:Ps help the following qns. Many tks and God Bless:)

(2) Jason and Ricky have 276 marbles altogether. 1/4 of Jason's marbles is 15 more than 1/5 of Ricky's marbles.
(a) How many marbles does each boy have?
(b) Find the ratio of the number of Ricky's marbles to the number of Jason's marbles.
If Rick's has 5u, 1/4 of Jason would be u+15. Which makes Jason total to be 4u +60

Total = 276 = 5u +4u +60
276 = 9u + 60
216 = 9u
u = 24

Jason = 5u = 120
Ricky = 4u + 60 = 156

b) R : J => 156 : 120 => 13: 10
Tks Ender for the 2 answers!

sushi88
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Re: Q&A - PSLE Math

Post by sushi88 » Wed Mar 30, 2016 11:07 am

SOS mum wrote:Tks Sushi88
However, when i used the same concept for the following qn, it cldnt solve. Ps help. Tks and God Bless:)

The ratio of the number of muffins to the number of pies in a bakery was 4:1. After another 63 muffins and 46 pies were baked, the ratio became 3:1. How many muffins and pies were there in the bakery at first?
SOS mum, actually the method works for this question too. Concept of ratio to find u. Only difference is previous question wants to find only one item, girls at first so multiply the u for the girls' part only but this question wants to find total items so multiply the u for total parts after u is solved.

Before:
M:P
4u: u
After:
M: P
4u+63: u+46
3 : 1

(4u+63)/ (u+46) = 3/1
4u+63 = 3(u+46)
4u+63 = 3u+138
u = 138-63=75

Hence total muffins and pies at first is 5u = 5 x 75 = 375

sushi88
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Re: Q&A - PSLE Math

Post by sushi88 » Wed Mar 30, 2016 11:42 am

SOS mum wrote:Ps help the following qns. Many tks and God Bless:)

(1) The total number of game cards that Fandi and Geetha had was the same as the number that Eugene had. The total number of game cards that Eugene and Geetha had was 5 times the number that Fandi had.
(a) What was the ratio of the number of game cards that Eugene had to the number of game cards that Geetha had to the number of game cards that Fandi had?
(b) Eugene had 118 game cards more than Fandi. How many game cards did the 3 children have altogether?
Alternative method using diagram.

Image

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