Tag Archives: Singapore

Primary 2 Whole Numbers Level 1 Ex 1

P2-Whole Numbers-L1-Ex 1

Ans:

1–  1

2–  3

3–  2

1 rec­tan­gle –>  16 ÷ 2 = 8

8 + 3 = 11

 

4–  3

9 + 3 + 9 + 3 = 24

24 ÷ 4 = 6

 

5–  2

6–  4

7–   Con­tinue read­ing

  

Primary 6 Algebra Level 1 Ex 4

P6-Algebra-L1-Ex 4

Ans:

1–  1

2–  1

3–  4

12x + 19 + (4x × 6 ÷ 3) – 8
= 12x + 19 + 8x - 8 = 20x + 11

 

4–  2

5–  2

Amount left after giv­ing her daugh­ter —  $(800 — 40z)

Each son ->  $(800 — 40z) ÷ 3

Con­tinue read­ing

  

Primary 4 October Problem Sums 4

P4-Oct-PSP-Ex 4

Ans:

1–  208 chicken pies

2–  17  1/3 kg

3–  $144

Qn

 

1u –>  $36 + $36 = $72

$72 × 2 = $144

 

4–  7 cm

Area of big rec­tan­gle –>  14 cm × 9 cm = 126 cm²

Area of unshaded rec­tan­gle –>  126 cm² — 98 cm² = 28 cm²

Length of AB –>  28 cm² ÷ 4 cm = 7 cm

 

5–  35 min­utes

Time the piano les­son ended —>  1h 40 min after 11 30 –>  13 10

Time dura­tion between 13 10 and 13 45 —>  35 min­utes

 

6–  32.5 kg

Ali­son + Brenda –>  61.5 kg
Ali­son + Chris­tine –>  67 kg
Brenda + Chris­tine –> 63.5

61.5 kg + 67 kg + 63.5 kg = 192 kg

A + A + B + B + C + C –>  192 kg

A + B + C –>  192 kg ÷ 2 = 96 kg

96 kg — 63.5 kg = 32.5 kg

Con­tinue read­ing

  

Primary 3 October Review 1

P3-Oct-Review 1

Ans:

1–  2

2–  1

3–  4

4–  4

5–  1

6–  2

7–  2

Total length of Parts A and B –>  21 m — 9 m = 12 m

Qn 7

3u –>  12 m

1u –>  4 m

Con­tinue read­ing

  

Primary 5 Volume Level 3 Ex 2

P5-Volume-L3-Ex 2

Ans:

1–  32 768 cm³ 32.768 l

3/4 — 5/8 = 1/8 poured out

1/8 × 64 cm × 64 cm × 64 cm = 32 768 cm³ / 32.768 l

 

2–  16 800 cm³16.8 l

3–  300 ml

4/5 — 1/2 = 3/10 filled

3/10 × 10 cm × 10 cm × 10 cm = 300 cm³ = 300 ml

 

4–  720 ml

8 cm — 5 cm = 3 cm

Amount of water poured out –>  40 cm × 30 cm × 3 cm = 3600 cm³

3600 cm³ ÷ 5 = 720 cm³ = 720 ml

 

5–  25 cm

Length   :   Breadth
4        : 1

4u — 1u = 3u

3u –>  6 cm

1u –>  2 cm –>  breadth

Length –>  2 cm × 4 = 8 cm

Base area –>  2 cm × 8 cm = 16 cm²

400 ÷ 16 = 25 cm

 

6–  17.5 cm

1600 cm³ ÷ 640 cm² = 2.5 cm

2.5 cm + 15 cm = 17.5 cm

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Time Management

With the PSLE just around the cor­ner, this is a great time to remind all the kids tak­ing the Maths paper to work on their time man­age­ment. I always feel it would help if I had an extra 10 minutes.

 

Paper 1 -> 30 ques­tions, 50 minutes

50 ÷ 30 ≈ 1.6 min per question.

 

Paper 2 -> 18 ques­tions (5 Short-answer ques­tions + 13 Long-answer ques­tions), 1 hour 40 min

SAQ -> 15 min

15 ÷ 5 = 3 min per question

LAQ-> 1 hour 25 min

85 ÷ 13 ≈ 7.5 min per question

Well, even with this esti­ma­tion, the kids have to be really metic­u­lous with their work as I have not left any time for check­ing. Ide­ally, of course, it would be good to leave 15% of the time allo­cated to do some checking.

Well, good luck to the kids tak­ing the PSLE! The next few weeks, make sure they are famil­iar with all the com­mon prob­lem sums. They should be well-prepared for Paper 1 too. Noth­ing less than 34/40 !

Image

  

Primary 5 September Review 1

P5-Sep-Review 1

Ans:

1–  3

2–  2

3–  3

4–  4

7u –> $756

1u –> $108

10u–>  $108 × 10 = $1080

 

5–  1

6–  3

80% –> $1800

1% –>  $22.50

100% –>  $22.50 × 100 =  $2250

Con­tinue read­ing

  

Primary 4 August Review 4

P4-Aug-Review 4

Ans:

1–  3

2–  3

3–  2

4–  4

5–  4

7.25 a.m. to 9.25 a.m (2 hour) –>  8 quarter-turns

8.25 a.m. to 9.40 a.m. (15 min) –>  1 quar­ter turn

8 + 1 =

Con­tinue read­ing

  

Primary 6 August Review 6

P6-Aug-Review6

Ans:

1–  4

2–  1

Total of the 4 num­bers –>  4 × 22 = 88

88 — 24 — 26 — 28 = 10

 

3–  1

4–  4

15/60 × 300 km = 75 km

75 km = 75 000 m

 

5–  4

6–  4

5/5 — 2/5 = 4/5  (owned cats and dogs)

3/5 –>  48 + 72 = 120 children

1/5 –>  40 children

5/5 –>  40 × 5 = 200 chil­dren

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Primary 5 Average Level 3 Ex 4

P5-Average-L3-Ex4

Ans:

1–  432 more stamps

Total num­ber of stamps Jamie and Patrick had ->  360 × 2 = 720

Patrick -> 1u

Jamie -> 4u

5u –>  720 stamps

1u –>  144 stamps

4u — 1u = 3u

3 × 144 = 432 more stamps

 

2–  71.5 kg

Total mass of 3 boys if they weigh as much as Derek –>  75 × 3 + 12 + 9 = 246 kg

Derek’s mass  –>  246 kg ÷ 3 = 82 kg

Joe’s actual mass ->    82 kg — 12 kg = 70 kg

Ron’s actual mass ->  82 kg — 9 kg = 73 kg

Aver­age mass of Joe and Ron –>  (70 + 73) ÷ 2 =  71.5 kg

3–  5.8 m

Total mass of the pole, plank and rod –>  4.8 m × 3 = 14.4 m

Rod –> 1u

Pole –> 2u

Plank –>  2u + 0.4 m

5u +  0.4 m ->  14.4 m

5u –>  14.4 m — 0.4 m = 14 m

Rod  –>  14 m ÷ 5 = 2.8 m

Pole –>  2.8 m × 2 = 5.6 m

Plank –>  2.8 m × 2 + 0.4 = 6 m

Aver­age length of pole and plank –>  (5.6 m + 6 m ) ÷ 2 = 5.8 m

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