This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

Thursday, May 08, 2008

Ai Tong School P6 SA1 2006 Math (Q39)

At a furniture sale, Mrs Devi paid $140 for two chairs and one coffee table. Mrs Siti paid $160 for one chair and two coffee tables. What is the cost of one chair?


C ----- Chair
T ----- Coffee Table

(Mrs Devi) C C T ----- $140
(Mrs Siti) C T T ----- $160

If Mrs Devi bought twice the number of chairs and tables, the chairs, coffee tables and amount paid would be doubled……

(Mrs Devi x 2) C C C C T T ----- $280
(Mrs Siti) C T T ----- $ 160

Note that Mrs Devi paid, $280 - $160 = $120, more than Mrs Siti.

This extra $120 paid by Mrs Devi more is due to the 3 extra chairs she bought more than Mrs Siti.

3 chairs ----- $120
1 chair ----- $120 divided by 3 = $40

Answer: The cost of one chair is $40.


keentolearn said...

Dear Mr Song

Guess and Check is one of many Problem Solving Heuristics. This strategy works on many types of problems but it is laborious. Therefore, it may not be efficient in examinations where time management is important.

Wish to seek your opinion on the use of Guess and Check as a Problem Solving Heuristics.

Excel Eduservice said...

Another method is to consider the differences between the 2 variables or otherwise known as "assuming method".

Here is an example of that.

Assuming Method

Disadvantage about this method is that not all students are able to understand the mechanics. However, if you do understand, it saves a lot of your time.