ACS Primary 2009 PSLE Math Prelim Paper 2 Q10

Given that the length of DB is 14 cm and the shaded region is 115 square cm, find the lenght of AC, correct to 2 decimal places.

Solution

Area of Triangle = Half base x height.
Area of Triangle ABC --> (1/2)(AC)(DX + 14)
Area of Triangle ACD --> (1/2)(AC)(DX)

Area of shaded area
--> Area of Triangle ABC - Area of Triangle ACD = 115

(1/2)(AC)(DX + 14) - (1/2)(AC)(DX) = 115

(1/2)(AC)(DX) + (1/2)(AC)(14) - (1/2)(AC)(DX) = 115

(1/2)(AC)(14) = 115
7(AC) =115
AC = 115 divided by 7
= 16.428
~ 16.43 (nearest to 2 decimal places)

Answer: 16.43 cm

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ACS Primary 2009 PSLE Math Prelim Paper 2 Q9

The pie chart below shows the different types of muffins sold in a bakery. A total of 240 muffins were sold.

a) How many banana muffins were sold?
b) If a chocolate muffin cost $1.60, how much did the bakery collect from the sale of chocolate muffins?

Solution

a) (1/4) x 240 = 60

Answer: 60 banana muffins


b)
Cheese --> (1/8) x 240 = 30
Blueberry --> (20/100) x 240 = 48
Banana --> 60
Chocolate Chip --> 68

Total for the above
--> 30 + 48 + 60 + 68 = 206

Chocolate --> 240 - 206 = 34

Sale collected from chocolate muffin
--> 34 x $1.60 = $54.40

Answer: $54.40

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ACS Primary 2009 PSLE Math Prelim Paper 2 Q8

The ratio of the number of pencils to the number of erasers in a box was 2:3. When 42 pencils were added and 15 erasers were removed, the ratio of the number of pencils to erasers became 3:4. How many erasers were there left in the box?

Solution

Before
--> Pencils 2 units, Erasers 3 units

After 42 pencils added and 15 erasers removed
--> Pencils 3 parts, Erasers 4 parts

3 parts --> 2 units + 42 (x3)*
4 parts --> 3 units - 15 (x2)*

*(x3) and (x2) to give an equal number of 6 units for both equations.

9 parts --> 6 units + 126
8 parts --> 6 units - 30

9 parts - 8 parts --> 126 - (-30)
1 part --> 156
4 parts --> 4 x 156 = 624

Answer: 624 erasers

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ACS Primary 2009 PSLE Math Prelim Paper 2 Q7

A bar of chocolate is sold at $3.50 each or in packets of 4 at $12 per packet. Alice wants to buy exactly 38 bars of chocolate for a party. What is the least amount of money that Alice could have spent on the chocolates?

Solution

38 bars --> 36 bars + 2 bars
--> 9 packets of 4 bars + 2 individual bars
--> (9 x $12) + (2 x $3.50)
= $108 + $7
= $115

Answer: $115

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ACS Primary 2009 PSLE Math Prelim Paper 2 Q5

If it takes 1 worker 4 days to paint a flat, how many days will it take 8 workers to paint 4 flats if they all work at the same rate?

Solution

1 worker --> 1 flat, 4 days

8 workers --> 8 flats, 4 days
(8 workers give an output 8 times more)

8 workers --> 4 flats, 2 days
(Same 8 workers need only half the time for 4 flats)

Answer: 2 days

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ACS Primary 2009 PSLE Math Prelim Paper 2 Q4

Barry poured 230 ml of lemonade into a jug that already contained 1.6 litres of juice. He then poured out the drink equally into 3 cups. What is the volume of the drink in each cup?

Solution

0.23 + 1.6 = 1.83

1.83 divided by 3 = 0.61

Answer: 0.61 litre

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ACS Primary 2009 PSLE Math Prelim Paper 2 Q3

The circumference of a circular disc is 154 cm What is the radius of the circular disc?

Solution

154 cm = (22/7) d

d = (154cm)(7/22) = 49 cm

d = 49 cm divided by 2 = 24.5 cm

Answer: 24.5 cm

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ACS Primary 2009 PSLE Math Prelim Paper 2 Q2

Box X contains 6 times as many oranges as Box Y. Box Z contains 111 fewer oranges than Box X. If Box Y contains 1/3 the number of oranges in Box Z, find the total number of oranges in the 3 boxes.

Solution

X --> 6 units

Y --> 1 unit

Z --> 6 units - 111

(3x) Y --> Z (since Y contains 1/3 of Z, we need 3 of Ys to be equal to one of Z)

3 units --> 111

1 unit --> 111 divided by 3 = 37

(Total) 13 units - 111

--> (13 x 37) - 111

= 370

Answer: 370 oranges

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Request for help from a reader - 10 Jul 2010

Posted by a reader which can be found in this link.

Aden and John started jogging along a circular track. Aden started at Point X while John started at Point Y where the line XY formed the diameter of the circle. Aden and John jogged toward each other along the circular track from their respective starting point and first met at Point W which was 80 m from Point X. After they met for the first time, they continued jogging along the track and finally met again for the second time at Point Z which was 60 m from Point Y. Find the distance of the circular track. (Answer : 360 m)

Any kind soul would like to help? Please post solution here. Registration is not required.

Request for help - CHIJ St Nicholas 2009 Prelim Paper 2 Q17

Hello everyone, I received an email from a reader seeking some help. Below is the email reproduced unedited. Please feel free to help.

======================

Hi,
I am a regular reader of your blog "road-to-psle". I have 1 question from CHIJ St Nicholas 2009 Prelim Paper 2 Q17 that I cannot solve. I have asked many people including tutors and teachers but they also cannot solve. Can you please help me? The question:

At Carpark P. the number of lorries to that of vans was in the ralio 3: 7.
At Carpark Q, the number of lorries to that of vans was in the ratio 8: 9.
When 40% more lorries from an industrial park entered Carpark P and
20% of the vans at Carpark Q moved to Carpark P. there were 76 fewer
Iorries at Carpark P than at Carpark Q. How many vehicles were there
altogether at the two carparks finally? Ans:564

Thanks
John

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Please post solutions here.

http://www.atfreeforum.com/excel/viewtopic.php?p=5&mforum=excel#5