P5 Nanyang Primary SA2 Paper 2 Q16

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P5 Nanyang Primary SA2 Paper 2 Q16

Postby ck123 » Sun Oct 03, 2010 5:18 pm

Hi all,

Can help with the model for this question?

Q16) Ali, Bala, Clyde and Dingyi shared a box of pens. Ali received 20% of the total number of pens which Bala, Clyde and Dingyi received altogether. Bala received 50% of the total number of pens which Ali, Clyde and Dingyi received altogether. Clyde received 80% of the total number of pens which Ali, Bala and Dingyi received altogether. Dingyi received 6 pens. How many pens were in the box at first?

Thanks alot.

ck123
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Postby snowman.697 » Sun Oct 03, 2010 5:32 pm

I dont know about model, but you can use ratio for this... I remember posting a solution for a similar question before. Also, why is it that so many people fall over when it comes to this kinda qn

snowman.697
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Postby ck123 » Sun Oct 03, 2010 5:37 pm

Hi snowman.697

Do you mind solving this question for me cause i do not have any clue?

Thanks

ck123
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Re: P5 Nanyang Primary SA2 Paper 2 Q16

Postby WS1234567 » Sun Oct 03, 2010 9:00 pm

ck123 wrote:Hi all,

Can help with the model for this question?

Q16) Ali, Bala, Clyde and Dingyi shared a box of pens. Ali received 20% of the total number of pens which Bala, Clyde and Dingyi received altogether. Bala received 50% of the total number of pens which Ali, Clyde and Dingyi received altogether. Clyde received 80% of the total number of pens which Ali, Bala and Dingyi received altogether. Dingyi received 6 pens. How many pens were in the box at first?

Thanks alot.


A: B+C+D =1:5
B: A+C+D =1:2
C: A+B+D =4:5

The total number of units in all three ratios above shd be the same since they're referring to the same total.
So, by making the total number of units the same by using lowest common multiple which is 18, the ratios become...
A: B+C+D =1:5 = 3:15
B: A+C+D =1:2 = 6: 12
C: A+B+D =4:5 = 8: 10

Therefore, A:B:C: D = 3:6:8:1
Now, 1u=6 pens
18u=6 x 18 =108 pens in total. (answer)

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