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Monday, May 29 2017 @ 06:23 AM CDT
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 P5 Percentage Question
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By: lbselaine (offline)  Tuesday, August 14 2012 @ 08:46 AM CDT (Read 911 times)  
lbselaine

Hi,

Can someone kindly teach me how to solve this qns? I need to teach my son who have problem solving it.

Qns:
Tom had 20% more marbles than Gary.
Billy had 25% fewer marbles than Tom.
If Billy and Gary had 1520 marbles, how many marbles did the 3 boys have altogether?

Thanks in advance.

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By: echeewh (offline)  Tuesday, August 14 2012 @ 09:19 PM CDT  
echeewh

Hey Elaine

Following pls find my worked solution:

Since T had 20% more than G, this means T had 120% compared to T (who had 100%). In ratio format, we have ...

T : G
120 : 100


Given B had 25% fewer than T, this means B had 75% compared to T (who had 100%). From above ratio, T had 120u. So we have ...

(T) 100% --> 120u
(B ) 75% --> (120/100) x 75 = 90u

So the ratio will be as follows:

T : G : B
120 : 100 : 90
12 : 10 : 9

Given B+G = 1520 marbles, we have ...

B+G = 9u + 10u --> 1520
19u --> 1520
1u --> 80

Hence, total (T+G+B ) = 12u + 10u + 9u = 31u
31u --> 31 x 80 = 2480

Total marbles of the 3 boys = 2480

================

Trust this helps

Do let me know again if this does not match your Answerkey or if theres any clarification.

Cheers,
Edward

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By: lbselaine (offline)  Sunday, August 19 2012 @ 08:17 PM CDT  
lbselaine

Hi Edward,

Thanks for the detail explanation.

I took the incorrect ratioas :

T = 120
G = 100
B = (120-25) = 95 which is incorrect.


Regards,
Elaine

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