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primary 5 | Maths | Rate & Ratio
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Jasmine
Jasmine

primary 5 chevron_right Maths chevron_right Rate & Ratio chevron_right Singapore

Please help to solve, thanks

Date Posted: 1 week ago
Views: 11
snell
Snell
1 week ago
before
T: 4u
R: 5u
S: 320-4u-5u = 320-9u

after
T: 4u
R: 5u/2
S: 160-9u/2

4u + 5u/2 + 160-9u/2 = 220
u = 30

(a)
ratio = 75 : 120 = 5 : 8


(b)
at first, S has 50 clips.


...
J
J
1 week ago
Rina : Tina = 5 : 4

5 cannot be divided equally by 2.
So change the ratio by multiplying by 2.

Rina : Tina = 5 : 4 = 10 : 8

Now Rina lost ½ her clips
½ of 10 units = 10units ÷2 = 5 units

Since 1 - ½ = ½
She has ½ of her clips left, which is 5 units.

Tina didn't lose any clips and remains at 8 units.

So the ratio now is 5 : 8


b)


At first, total clips = 320 clips
In the end, total clips = 220 clips

Lost clips = 320 - 220 = 100 clips

Since Rina and Selena both lost ½ their clips,

½ of Selena's clips + ½ of Rina clips
= 100 clips

So Selena's clips + Rina's clips at first is twice of that

= 100 clips x 2 = 200 clips

Tina's clips at first (and in the end also since she didn't lose any)
= 320 - 200 = 120

120 clips = 8 units
1 unit = 120 clips ÷ 8 = 15 clips

Rina's clips at first
= 10 units
= 10 x 15 clips
= 150 clips

Selena's clips at first

= 200 clips -150 clips
= 50 clips