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.

## Monday, June 30, 2008

### S’pore Hokkien Huay Kuan 2007 PSLE Math Prelim Q37

The rectangle is divided into 4 parts. Each part has a different area. Find the area of X.

Area of X ----- 4 cm x 3 cm = 12 square cm (Answer)

Note – “The Singapore Hokkien Huay Kuan 5-School Combined Prelim Maths” is the common Maths Prelim Exam for Tao Nan, Ai Tong, Chongfu, Nan Chiau and Kong Hwa schools.

## Sunday, June 29, 2008

### Ai Tong School P6 SA1 2006 Math (Q48)

The figure below shows a circle and two quadrants enclosed within a square. O is the centre of the circle. Find the total area of the shaded parts in the figure shown. (Take =3.14)

Solution

Redrawing…..

Area of A ----- Area of small square – Area of small quadrant

= (10 cm x 10 cm) – (3.14 x 10 cm x 10 cm x ¼)
= 100 square cm – 78.5 square cm
= 21.5 square cm

Area of 1 shaded portion ----
Area of large square – Area of large quadrant – Area of A

= (20 cm x 20cm) – (3.14 x 20 cm x 20 cm x ¼) – 21. 5 square cm
= (400 – 314 – 21.5) square cm
= 64.5 square cm

Area of total shaded portion therefore is 64.5 square cm x 2 = 129 square cm (Answer)

## Thursday, June 26, 2008

### Ai Tong School P6 SA1 2006 Math (Q47)

The figure shown below is made up of a square, a rectangle and a right-angled triangle. The area of the square MNQR is 49 square cm and the area of the rectangle NOPS is 60 square cm. OP is 4 cm.
(a) Find the length of MR
(b) Find the length of SP
(c) Find the area of the triangle PSQ

Solution

(a)
Area of square MNQR = 49 square cm.
1 side is therefore 7 cm (7 x 7 =49)

(b)
Area of rectangle NOPS is 60 square cm.
60 square cm = SP x 4 cm
SP = 60 square cm divided by 4 cm = 15 cm

(c)

NQ = 7 cm, therefore
SQ = 7 cm – 4 cm = 3 cm

Area of triangle PSQ = ½ x base x height
= ½ x 15 cm x 3 cm
= 22.5 square cm

## Friday, June 13, 2008

### Ai Tong School P6 SA1 2006 Math (Q46)

Shop X sells a handbag for \$520. This price is 30% more than the price which Shop Y sells it for.
(a) What is the price of the handbag in Shop Y?
(b) During a sale, both shops offer an equal percentage discount on the handbag. Miss Lee buys the handbag in Shop Y. She pays \$90 less than the discounted price in Shop X. What is the percentage discount?

Solution

Shop X ----- 100% + 30% ----- \$520
Shop Y ----- 100%

(a)
130% ----- \$520
100% ----- \$520 divided by 1.3 = \$400

Answer: The price of the handbag in Shop Y is \$400.

(b)
Before discount, the price difference between Shop X and Shop Y is \$120.

After discount, the price difference is \$90.

The \$30 decrease in difference is due to the same percentage discount at both shops.

Discount ----- \$(30/120) x 100% = 25%

Answer: The percentage discount is 25%.

## Tuesday, June 10, 2008

### Ai Tong School P6 SA1 2006 Math (Q45)

Jack and Glen shared some stickers in the ratio of 3 : 1. Jack gave away 66 stickers and the number of stickers he had left was 4/5 of Glen’s share of stickers. How many stickers had Jack at first?

Solution

11 units ----- 66
1 unit ----- 66 divided by 11 = 6
15 units ----- 15 x 6 = 90

### From the ST Forum

'Sure fail' exams: Apply them sparingly

AS A 16-year-old, I have been through my fair share of examinations. It is no myth that national exams are becoming more difficult as the years go by. Schools, including mine, are setting more difficult internal exams to prepare their students for these rigorous national ones. Advantages of this practice include equipping students with the necessary practice and skills to successfully attempt more challenging questions.

Singaporeans must realise the world is becoming more competitive. Nowadays, an average student is not one who scores Cs but one who scores As and Bs. Educational qualifications are gaining importance and schools are only trying to give their students enough experience to tackle national exams with ease.

However, schools must justify setting these 'sure-fail' exams, implying they must have prepared their students for the difficulty of internal exams. While difficult questions are known as a test to discover the most able students, the average student must be sufficiently prepared to sit for difficult internal exams and pass. Schools with an average mark of 40 per cent in a certain subject have evidently not prepared their students for the difficulty of such exams.

While this scare tactic may have worked in the past, it does not any more. Students can deal with failure once or twice, but when the average student fails constantly, he will probably give up completely. This will destroy his love of learning and the education system will have failed him.

Schools have every right to maintain high standards and push their students to achieve academic excellence. A small amount of pressure can be helpful in any pursuit. However, this tactic should not be overdone and not at the price of students' well-being. Schools have to prepare their students sufficiently for challenging internal exams to provide a healthy learning environment and inculcate a zest for learning. This can be achieved only with positive motivation. I am confident this will boost not only students' confidence, but their results as well.

Thara Rubini Gopalan (Miss)

## Friday, June 06, 2008

### Majestic Niagara Falls

Besides being a tourist attraction, Niagara Falls is also known to generate electricity for both Canada and US.

Hydro Electric Power is electricity generated by water. A dam is built to increase the height of the water. As the height of the water increases, gravitational potential energy increases. Water at the bottom of the dam thus experiences high pressure. This causes the water to be released at a high speed, with a lot of kinetic energy.

The kinetic energy is then used to turn the turbine, which then turns the generator to produce electricity.

Pictures of Niagara Falls.

Rainbow Falls, on the US side of the border

Horseshoe Falls, on the Canadian side of the border. Yes, we all got wet as the boat approached the falls.

A couple more shots of the falls below.

Picture shot of the dam at the Hydro Electric Power Plant, on the Canadian side of the border. (below)

The dam is situated a few kilometres downstream of the falls.

That's all for now.

## Wednesday, June 04, 2008

### In the countryside – Midlands, Ontario, Canada

Trees and other plants play an important part in our environment. When they make their own food through photosynthesis, they produce oxygen for all living things to respire.

In the winter, most trees lose their leaves.

In the summer, green leaves are everywhere in sight.

Earthworms are important to the environment. They help aerate the soil and aid plants by dragging leaves into the soil – which will serve as nutrients for the plants.

Here are some other things you can find in Midlands. Fairytale Land!

That's all for now.