Primary 5 CA1 Revision 12featured

P5-CA1-Ex12

Ans:

1–  $384

Christina –>  1u

Molly ->  3 u

Jack –>  1u + $65

5u + $65 = $705

5u –>  $705 – $65 = $640

1u –>  $640/5 = $128

$128 × 3 = $384

 

2–  235 paper clips

Before:                      Tom               :                   Jenny
1                   :                           5

——->     2                  :                         10

After:                             1                   :                           2

——>      5                  :                       10

5u – 2u = 4u

3u –>  141 clips

1u –>  47 clips

47 × 5 = 235 paper clips

 

3–  $60

3u –>  $36

1u –>  $12

$12 × 5 = $60

 

4–  9 years’ time

[Constant Difference]

3u –>  51 years

1u –>  17 years old

17 – 8 = 9 years’ time

 

5–  See belowQn 5

 

 

 

 

 

 

 

 

 

6–  18 coins

Multiples of 5 –>  5         10           15
+ 3  ->  8         13           18

Multiples of 4 –>   4         8             12            16
+ 2 ->   6         10          14           18

7–  660 ducks

Number of ducks sold on the 1st day ->  3/7 × 840 = 360

Remaining number of ducks –>  840 – 360 = 480

Number of ducks sold on 2nd day –>  5/8 × 480 = 300

300 + 360 = 660 ducks

 

8–  1  7/10 kg

Jar + 1 u –>  2  1/2 kg

Jar + 6u –>  6  1/2 kg

5u –>  4 kg

1u –>  4/5 kg

2  1/2 kg – 4/5 kg = 1  7/10 kg

 

9–  $28

1 bag + 1 book –>  $21

1 book –>  1u

1 bag –>  1u + $15

2u ->  $21 – $15 = $6

1u –>  $3

$3 + $15 = $28

 

10–  50 more days

Number of pages Damien read each day –>  115 ÷ 5 = 23

Total number of days –>  1265 ÷ 23 = 55 days

55 – 5 = 50 more days

 

11–  $51 606

Area of rectangular field –>  46 m × 32 m = 1472 m²

Area of unshaded rectangle –>  22 m × 17 m = 374 m²

Area of shaded part –>  1472 m² – 374 m² = 1098 m²

1098 m² × $47 = $51 606

 

12–  $44

Qn 12

 

 

 

 

3u –>  $9 + $15 + $9 = $33

1u –>  $11

$11 × 4 = $44

 

13–  T-Shirt ->  $30  ,  Shorts – >  $24

Cost of 2 shorts and 2 T-shirts –>  $192 – $84 = $108

Therefore, 4 pair of shorts and 4 T-shirts –>  $108× 2 = $216

1 pair of shorts –>  $216 – $192 = $24

1 pair of shorts + 1 T-shirt –>  $108 /2  = $54

1 T-shirt –>  $54 – $24 = $30

 

14–  289 marbles

Red   :   Blue                                            Green   :   Red
1      :      3                                                      1       :      4
–>           4      :     12                                                     1      :       4

Green   :  Red   :   Blue
1       :     4      :   12

12u – 4u = 8u —->  136 marbles

1u –>  17 marbles

17 × 17 = 289 marbles

 

15–  $42

Qn 15

 

 
7u –>  $66 – $10 = $56

1u –>  $8

$8 × 4 + $10 = $42

 

16–  a ->  105 roses  ,    b-> 10/31

Fraction of red roses –>  3/5 × 2/3 = 2/5

Fraction of white roses –>  1 – 1/3 – 2/5 = 4/15

Pink roses –>  1/3 = 5/15

Red Roses –>  2/5 = 6/15

White roses –>  4/15

6u – 4u = 2u –>  14 roses

1u –>  7 roses

7 roses × 15 = 105 roses   (a)

Red roses at first –>  6 × 7= 42

42 – 12 = 30 red roses left

105 – 12 = 93 roses left

30/93 = 10/31        (b)

 

17– $549

2 handbags + 6 pairs of shoes–>  $1485 – $867 = $618

1 handbag + 3 pairs of shoes –>  $618/2 = $309

8 handbags –>  $1485 – $309 = $1176

1 handbag –>  $147

3 pairs of shoes –>  $309 – $147 = $162

1 pair of shoes –>  54

$(147 × 3) + $(54 × 2) = $549

 

18–  $2

Fraction of money left –>  7/12 × 4/5 = 7/15

Fraction of money spent on the calculators –>  1/5  = 3/15

7u –>  $350

1u –>  $50

$50 × 3 = $150

Price of 1 calculator –>  $150 ÷ 25 = $6

$6 ÷ 3 = $2

 

 

 

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