Q&A - PSLE Math

[tianzhu]

Dad8282:

2. Rectangle A overlaps with Rectangle B. Rectangle A is twice the size of Rectangle B.
If 1/3 of Rectangle B overlaps with Rectangle A, what fraction of Rectangle A
overlaps with Rectangle B?

Thanks.

Hi

A neat way is to use MD or draw two boxes of different sizes and labeling them with units.

Draw 6 boxes to show the size of rectangle A. Use 5 boxes to show its unshaded portion and 1 box to show the shaded portion.

Draw 3 boxes to show the size of rectangle B. Use 2 boxes to show unshaded area, the shaded portion is the same as rectangle A.

Hence, fraction of A overlapping B ------ 1/6

Best wishes

[Dad8282]

Good Morning Tianzhu,


Thank you for your explanation and pointing me to the correct page for the answer!

Have a nice day!

[mathnoobs]

Hi Mathizzfun

I recently came across this problem and found that you have the answer. http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=7640


Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

However, I don't quite understand this line:
Work needed to complete job --> 12 units

how do you get the 12 units ? thanks in advance.

[dazzlego]

mathnoobs:

Hi Mathizzfun

I recently came across this problem and found that you have the answer. http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=7640


Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

However, I don't quite understand this line:
Work needed to complete job --> 12 units

how do you get the 12 units ? thanks in advance.

I guess he assume that the number of work done is the LCM of 4, 6 and 12. Since A+B = 4 days, B+C = 6 days, A+C = 12 days

[charsen]

dazzlego:

mathnoobs:

Hi Mathizzfun

I recently came across this problem and found that you have the answer. http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=7640


Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

However, I don't quite understand this line:
Work needed to complete job --> 12 units

how do you get the 12 units ? thanks in advance.

I guess he assume that the number of work done is the LCM of 4, 6 and 12. Since A+B = 4 days, B+C = 6 days, A+C = 12 days

Hi
Dazzle go,your explanation is correct.

[MathIzzzFun]

mathnoobs:

Hi Mathizzfun

I recently came across this problem and found that you have the answer. http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=7640


Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

However, I don't quite understand this line:
Work needed to complete job --> 12 units

how do you get the 12 units ? thanks in advance.

We need to find the work rate in units/day. So, in order to \"avoid\" working in fractions, set the amount of work done (in assembling the aircraft) to be the LCM of 4,6 & 12

cheers.

[mathnoobs]

MathIzzzFun:

mathnoobs:

Hi Mathizzfun

I recently came across this problem and found that you have the answer. http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=7640


Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

However, I don't quite understand this line:
Work needed to complete job --> 12 units

how do you get the 12 units ? thanks in advance.

We need to find the work rate in units/day. So, in order to \"avoid\" working in fractions, set the amount of work done (in assembling the aircraft) to be the LCM of 4,6 & 12

cheers.

I see. thanks, I understand now why LCM is used.

[riot_r6]

Hi, have a question on the methods that are acceptable on PSLE maths.


My son’s tutor is teach him to use simultaneous equation to solve some of the problem solving questions, can this be used during exam? Would marks be deducted?

[speedmaths.012624com]

riot_r6:

Hi, have a question on the methods that are acceptable on PSLE maths.


My son's tutor is teach him to use simultaneous equation to solve some of the problem solving questions, can this be used during exam? Would marks be deducted?

Hi,

Please see letter/reply from MOE below.

Cheers

speedmaths.com

=

17 Feb 2007

Different Approaches Taught for Mathematics Techniques

1.\tMr Lim Boon Tong had sought clarification on whether mathematics techniques like algebra, other than the model drawing method, could be used in the Primary School Leaving Examination (PSLE) Mathematics. (“Can algebra be used to solve PSLE maths problems”, The Straits Times, 12/2/2007).

2.\tThe model drawing method is a powerful approach for problem solving and learning mathematical concepts. By drawing models, pupils can represent the mathematical relationships in a problem pictorially. This helps them understand the problem and plan the steps for the solution.

3.\tThe pictorial form also helps pupils visualise what could otherwise be abstract concepts. In this way, model drawing supports the learning of fractions, ratio and percentages. Pupils will find model drawing useful when they solve problems involving these concepts in Primary Five and Six.

4.\tThe model drawing method is thus a developmentally sound approach for young children. It is recognised internationally as an effective way for young children to learn problem solving and to have early exposure to algebraic concepts. At Primary Six and Secondary One, pupils can draw upon their earlier experience of using models to help them understand algebraic relationships in problems.

5.\tOther than the model drawing approach, pupils are also taught different problem solving methods. They are encouraged to try different approaches and have the flexibility to choose the method that works best for them in solving the problems. They are also encouraged to present their solutions clearly so that these can be understood.

6.\tWhile pupils are not required to use algebra to solve word problems in the PSLE Mathematics, they are also not restricted to the use of any one particular method. In the marking of PSLE Mathematics, all mathematically correct solutions are acceptable and there is no loss of marks if a correct algebraic method is used.

7.\tWe thank Mr Lim for his feedback.

Ho Peng (Ms)
Director, Curriculum Planning and Development
Ministry of Education

Tan Yap Kwang
Chief Executive
Singapore Examinations and Assessment Board


.

[Bingu]

Hi there,

Can someone please help in the below math question:

Leon bought some terrapins and guppies for a total of $96. He bought 3 times as many guppies as terrapins.
He paid $30 more for the terrapins than for the guppies.
Each terrrapin cost $10.40 more than each guppy.
a) How many terrapins did he buy?
b) what was the cost of each guppy?