Q&A - PSLE Math

[abc_parent]

Hi everyone - please help


Q6) Muthu and Beng Huat had some money. If Muthu gave Beng Huat $360. both would have an equal amount of money. If Beng Huat gave Muthu $180, Beng Huat would have 1/3 as much money as Muthu.
(a) How much money did Muthu have?
(b) How much money did Beng Huat have?

Ans:(a) $1440 (b) $720


Q9) Mr Kuah, a canteen vendor, had a container completely filled with oil. On the first day, he used 1 litre more than 1/2 of the original amount of oil in the container for his cooking. On the second day, he used 2 litres more than 1/3 of the remaining oil in the container. On the third day, he used 6 litres more than 1/7 of the oil left in the container. In the end, there were still 6 litres of oil in the container.
How many litres of oil were there in the container at first?

Ans: 50 litres


Q12) Given that p : (q+r)=1:3, r : (q+s)=1: 2 and p : s=2 : 5.
(a) p:q:r:s
(b) Find (r+q) : (p+s)

Ans:
(a) 6 : 7 : 11 : 15
(b) 6 : 7


Q16) [There is a diagram for this question. Please help if you have it]
The figure below consists of three circles. The smallest circle has centre O and radius of 4cm. The biggest circle has centre O and radius of 10cm. The diameter of the biggest circle also cuts through the centre of the medium-sized circle. The medium-sized circle touches the other two circles as shown. The three regions formed are coloured red, white and blue as shown.
(a) Find the radius of the medium-sized circle.
(b) Find the area of the white region. Use a calculator to obtain the value of pi. (Give your answer correct to 2 decimal places.)
Express the area of the red region as a fraction of the area of the blue region.


Ans:
(a) 7cm (b) 103.67cm square 16/51


Q17)Ahmad started travelling from Town P towards Town Q at 7am. After travelling for some time, he passed Steve who was travelling at an average speed of 80km/h in the opposite direction. After travelling for another 2 hours, Ahmad reached Town Q while Steve was still 40km away from Town P.
(a) If Ahmad reached Town Q at 1pm, what was his average speed?
(b) If Steve started his journey from Town Q, at what time did he leave Town Q?

Ans
(a) 50 km/hour
(b) 9.45a.m.

Q18)Mdm Ang bought some highlighters, pens and mechanical pencils. 1/4 of them were highlighters. The number of pens she bought was 6 more than 1/2 the total number of all the items and the remaining were mechanical pencils. Each of the highlighters, pens and mechanical pencils cost $2.10, $4.05, $1.60 respectively. She spent a total of $227. 10 on all the items. How many pens did she buy altogether?

Ans:
42

[abc_parent]

Hi everyone - please help if you can.


Q6) Mrs Siva has some sweets. If she gives 5 sweets to each of her pupils, she will have 4 sweets left. If she gives 12 sweets to each of her pupils, she will need 73 more sweets. How many pupils are there?

Ans:
4 + 73 = 77
12 - 5 = 7
Pupils -> 77 / 7 = 11
There are 11 pupils. [I don’t understand the rationale.]


Q9) Find the value of
(3 + 5 + 7 + … + 21) / (40 + 60 + 80 + … + 360)

Ans: 3/85

Q13) The ratio of $2 notes to $5 notes in Joan’s piggy bank was 13: 8. She exchanged 20 pieces of $2 notes for some $5 notes, after which, the ration of $2 notes to $5 notes became 4:5. What was the total value of $2 notes and $5 notes in the piggy bank at first?

Ans: $264

Q15) [This question contains a picture. Please help if you have it.]
The figure below consists of 2 identical semicircles, a larger semicircle and a circle. The diameter of the big semicircle is 40cm. Find the shaded area. (Take pi = 3.14)

Ans: 228 cm square

Q16) The figure below shows a solid made up of 10 identical cubes. When the solid is painted black the total area being painted is 360 cm square.
(a) What is the volume of the solid?
(b) How many more cubes must be added to change this solid into a big cube with a volume of 729 cm cube?

Ans: (a) Volume is 270 cm cube.
(b) 17 cubes must be added.

[abc_parent]

Hi everyone - please help if you can.


Q7) The figures below, X and Y, are 2 identical isoceles triangles. Both figures contain a square of a different size. Given that the area of the square in Figure X is 360 cm square, find the area of the sqaure in Figure Y.

Ans: 320 cm square

Q9) [This question has a picture. Please help if you can.]
The figure below is not drawn to scale. PQRS is a square and CBRD is a rectangle. BRE is a straight line. Given that angle DRF= 136 degree and angle SHD = 129, find the ratio of angle HRB to angle ERF.

Ans: 51:46

Q15) A bullet train took 5 hours to travel from Patient Town to Honest Town while an electric train took 4 hours to travel from Honest Town to Patient Town. Both trains set off at the same time and moved towards each other. Two hours later, they were 255 km apart. What was the speed of the electric train?

Ans: 75 km/h

[abc_parent]

Hi everyone again - please help


Q4)[There is a diagram so please help if you have it]
Each link of a chain has an outside length of 40cm, and the metal is 4cm thick.
The diagram below shows a chain which is made up of 4 links. Find the maximum length, in cm, of a chain which is made up of 10 links.

Ans: 328 cm

Q12) Figure 1 below shows a rectangular tank containing 6 cubes and filled with water to its brim. In figure 2, four cubes were removed from the same tank and the water level dropped by 4.5cm. After that, a certain amount of water was drained off the tank until the water level reaches the same height as the remaining cubes. Find the volume of water in the tank in Figure 2.

Ans: 720 cm cube

Q13) The figure below is made up of 4 shaded parts formed by a circle and an isosceles triangle XYZ. The circle has a diameter of 12 cm and in the triangle XYZ, XY = XZ = 13cm and YZ = 10cm.
(a) Calculate the perimeter of the shaded parts.
(b) Calculate the difference between shaded parts ‘A’ and ‘B’.

Ans:
(a) 73.70cm
(b) 26.55cm square

Q17)Mr Tan took 6 h to drive from Town A to Town B.
Mr Lim who started at the same time as Mr Tan, took 4 hours to drive from Town B to Town A. When they met each other, they were 48km away from the midpoit of Town A and Town B.
(a) Calculate the distance between Town A and Town B.
(b) Calculate the speed of Mr Tan.

Ans:
(a) 480km
(b)80km/hour


Q18) 20% of John’s savings is $120 more than 30% of Brian’s savings. After John spent 5/6 of his savings and Brian spent 1/2 of his savings, John has $20 more than Brian. Find the savings of John at first.

Ans:
$1080

[abc_parent]

Hi again


Does anyone know where to find the complete step by step solutions for SCGS Prelims. Not sure how you feel about it but I cannot do most of the questions in paper 2.

There’s also much discussion about prelims 2010. May I know where I can find them and find the solutions?

Thanks in advance !!!

[tianzhu]

abc_parent:

Hi again


Does anyone know where to find the complete step by step solutions for SCGS Prelims. Not sure how you feel about it but I cannot do most of the questions in paper 2.

There's also much discussion about prelims 2010. May I know where I can find them and find the solutions?

Thanks in advance !!!!

Hi

If you want to buy 2010 P6 Preliminary papers, you may refer to this thread.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=6459&postdays=0&postorder=asc&start=330

Best wishes

[tianzhu]

abc_parent:

Q15) A bullet train took 5 hours to travel from Patient Town to Honest Town while an electric train took 4 hours to travel from Honest Town to Patient Town. Both trains set off at the same time and moved towards each other. Two hours later, they were 255 km apart. What was the speed of the electric train?
Ans: 75 km/h

Hi

I think it should be 4 hours longer(original question) instead of 4 hours.

A quick solution, as in any speed question, I suggest you draw a line diagram.

For bullet train, it took 5 hours to cover the journey.
In 1 hour, it travelled 1/5 of the journey

For electric train, it took 9 hours to cover the journey.
In 1 hour, it travelled 1/9 of the journey

In 2 hours time, the two trains covered (2/5 + 2/9) or 28/45 of the journey

45-28 --- 17
17 units --- 255
1 unit --- 15 km

Total journey --- 45U --- 45 x 15 ---675 km

The speed of electric train --- Distance/Time --- 675 / 9 --- 75 km/h

Best wishes

[tianzhu]

abc_parent:

Q16) [There is a diagram for this question. Please help if you have it]
The figure below consists of three circles. The smallest circle has centre O and radius of 4cm. The biggest circle has centre O and radius of 10cm. The diameter of the biggest circle also cuts through the centre of the medium-sized circle. The medium-sized circle touches the other two circles as shown. The three regions formed are coloured red, white and blue as shown.
(a) Find the radius of the medium-sized circle.
(b) Find the area of the white region. Use a calculator to obtain the value of pi. (Give your answer correct to 2 decimal places.)
(c) Express the area of the red region as a fraction of the area of the blue region.Ans:(a) 7cm (b) 103.67cm square (c) 16/51

Hi

For Q16, the more challenging part is finding the radius of the medium sized circle. Once a student is able to do it, the rest of the question is straightforward.

Hope this helps.

Best wishes

http://farm5.static.flickr.com/4107/4998225539_8b8d80a791_b.jpg\">

[Ler]

tianzhu:

Ler:

Q14. The diagram above, not drawn to scale, shows the dimensions of wheels of Kens bicycle. he pushed his bicycle down a slope 3m long. How many complete revolutions did the wheel make?
(sorry cant diagram)

Hi

To answer this question, you need to find the circumference of the wheel.

You may insert images by following the following steps.

1) Do a print screen of the portion you want to upload.

2) Edit using Paint. Cut out the portion of the question you want to upload.

3) Save file in pictures

4) Go to Flickr (Free sign up as member) or other storage sites. Upload file. Select biggest/medium size. Right click to copy URL of image.

5) Coming back to Kiasuparents forum, click insert image button.

Best wishes

Many thanks for teaching me about how to use above steps.

Ler

[tianzhu]

Ler:

Many thanks for teaching me about how to use above steps.

Hi

Yoy're welcome.

Best wishes