Tag Archives: problem sums

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

Con­tinue read­ing

  

Primary 4 July Problem Sums 3

P4-July-PSP-Ex 3

Ans:

1–  $9153

$2178 + $6975 = $9153

 

2–  5  5/12 kg

The total mass of the nails–>  9   11/12 kg —   11/12 kg = 9 kg

Mass of the nails when they are half-filled –>  9 /2 = 4   1/2 kg

4   1/2 kg +  11/12 kg = 5   5/12 kg

 

3–  3456 canned drinks

128 × 27 = 3456 canned drinks

 

4–  56.58 kg

Qn 4

6u –>  169.74 kg

1u –>  28.29 kg

28.29 kg × 2 = 56.58 kg

Con­tinue read­ing

  

Primary 6 July Problem Sums 6

P6-July-PSP-Ex 6

Ans:

1–  $800

Frac­tion of money spent on food and shoes –>  1/4 + 1/5 = 9/20

20/20 — 9/20 = 11/20

11u –>  $340 + $100 = $440

1u –> $40

20u –>  $40 ×  20 = $800

 

2–  14 cook­ies

Muffins   :   Cookies

At first  ——>           [   5             :         6   ]  × 2

In the end   ——>    [   2             :        1  ]  × 5

[Make the units of muffins at first and in the end the same]

Muffins   :   Cookies

At first  ———>             10          : 12

In the end  ——->           10          : 5

12u –>  24 cookies

1u –>  2 cookies

5u –>  10 cook­ies left

24 — 10 = 14 cook­ies 

 

3–  Joseph spent more by $2000

3/5 of Terry’s money is equal to 1/3 of Joseph’s money.

[Make the numer­a­tor common]

3/5 of Terry’s is equal to  3/9 of Joseph’s.

Terry   :   Joseph
5         : 9

14u –> $7000

1u –> $500

Amount Terry spent –>  $500 × 5 = $2500

Amount Joseph spent –>  $500 × 9 = $4500

$4500 — $2500 = $2000

Con­tinue read­ing

  

Primary 4 July Problem Sums 2

P4-July-PSP-Ex 2

Ans:

1–  $144

1/2 u –> $36

1u –>  $36 × 2 = $72

$72 × 2 = $144

 

2–  $487.80

3–  6  4/5 kg

4–  2637 more seashells
Qn 4

7u –>  6328 — 623 = 5705

1u –> 815

Jan­ice –>  815 × 7 = 4075 seashells

Car­o­line –>  815 + 623 =1438 seashells

4075 — 1438 =  2637 more seashells

Con­tinue read­ing

  

Primary 6 July Problem Sums 5

P6-July-PSP-Ex 5

Ans:

1–  95

[Use trial and error from the largest 2-digit mul­ti­ple of 9]

Great­est pos­si­ble 2-digit mul­ti­ple of 9 –> 99

99 + 5 = 104 (wrong: answer is not 2-digit)

90 + 5 = 95 (correct)

 

2–  100 grey squares and + 99 white tiles

Num­ber of grey tiles –> Pat­tern Num­ber × 2

50 × 2 = 100 grey tiles

Num­ber of white tiles –>  Num­ber of grey tiles — 1

100 — 1 = 99 white tiles

 

3–  108 teach­ers

Pupils  –>                      Boys  :  Girls
4     : 5

5u –> 2400

1u –> 280

9u –>  280 × 9 = 4320 children

Teach­ers  :  Pupils
1          : 40

40u –> 4320

1u –>  108 teach­ers

 

4–  14 years old

Nicholas’ age now –>  35 — 8 = 27 years old

Timothy’s age now –>  1/3 × 27 = 9 years old

9 + 5 = 14 years old

Con­tinue read­ing

  

Primary 5 July Problem Sums 1

P5-July-PSP-Ex 1

Ans:

1–  $2425
Qn 1

1u –>  $1600 + $750 = $2350

$2350 + $750 = $2425

 

2–  29/45

Amount Diane saves -> $1800 — $640 = $1160

1160/1800 = 29/45

 

3–  4  1/2 kg

Mass of apples when the bas­ket is com­pleted filled –>  8 kg — 1 kg = 7 kg

Mass of apples when bas­ket is 1/2 filled –>  7 kg ÷ 2 = 3  1/2 kg

3  1/2 + 1  = 4  1/2 kg

 

Con­tinue read­ing

  

Primary 4 July Problem Sums 1

P4-July-PSP-Ex 1

Ans:

1–  63 sweets

2–  $90

Qn 2

2u –>  $75 — $45 = $30
1u –> $15

$15 + $75 = $90

 

3–  96 cook­ies
Qn 3

5u –>  80 cookies

1u –>  16 cookies

6u –>  16 cook­ies × 6 = 96 cook­ies

 

4–  $68
Qn 4

3u –>  $48 + $12 = $60

1u –> $20

$48 + $28 = $68

Con­tinue read­ing

  

Primary 4 June Problem Sums 1

P4-Jun-PSP-Ex1

Ans:

1–  1120 stick­ers
Qn1

9u –>  1260 stickers

1u –>  140 stickers

8u –>  140 × 8 = 1120 stick­ers

 

2–  $28 125

Total num­ber of TV sets sold –>  15 × 5 = 75

$375 × 75 = $28 125 

 

3–  a ->  4 ostriches  ,   b ->  76 more legs

Qn3

 

84 — 8 = 76 more legs   (b)

Con­tinue read­ing

  

Primary 6 June Problem Sums 6

P6-PSP-Jun-Ex 6

Ans:

1–  60 stamps
Qn 1

4u –>  26 + 14 = 40

1u –>  40 ÷ 4 = 10 stamps

6u –> 10 × 6 = 60 stamps

 

2–  6.05 m

Total length of rope Edmond and Mandy had ->  24.6 m + 32.5 m = 57.1 m

57.1 m — 4.2 m = 52.9 m

Length of rope Mandy had in the end –>  52.9 m ÷ 2 = 26.45 m

32.5 m — 26.45 m = 6.05 m

 

3–  13 big water­mel­ons and 5 small watermelons

Assume all 18 water­mel­ons were small –>  18 × $3 = $54

$67 — $54 = $13 (excess)

Since each big water­melon cost $1 more–>  $13 ÷ $1 = 13 big watermelons

18 — 13 = 5 small watermelons

 

4–  See below
Qn 4

Con­tinue read­ing

  

Primary 5 May Problem Sums 2

P5-May-PSP-Ex 2

Ans:

1–  48 mar­bles

[Inter­nal difference/ Con­stant Total]

1u + 7u = 8u (total)

8u ÷ 2 = 4u

4u — 1u = 3u (units Casper received from Zachary)

3u –> 18

1u –> 6

8u –>  6 × 8 = 48 mar­bles

 

2–  $280

Num­ber of months Nikki took to save $7000 –>  $7000 ÷ $140 = 50 months

Num­ber of Months Stephanie took to save $7000 –>  50 — 25 = 25 months

$7000 ÷ 25 = $280

 

3–  732 fewer points

Qn 3

5u –>  1277 — (158 × 4)  = 645

1u –>  645 ÷ 5 = 129

(158 × 3) + (129 × 2) = 732 fewer points

 

4–  $90

Amount of money they had in the end–>  $150 — $20 — $50 = $80

$80 ÷ 2 = $40

$40 + $50 = $90

Con­tinue read­ing