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PostPosted: Thu May 07, 2020 3:51 pm 
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Joined: Sat Jun 30, 2018 11:46 am
Posts: 86
Hi

Is anyone able to explain the answer to this question please?

Isla's coin collection contains Mongolian, Algerian and Italian coins. If the ratio of Mongolian to Algerian coins is 3:2 and the ratio of Algerian to Italian coins is 7:6, what is the ratio of Mongolian to Italian coins?

The answer is 7:4

Any explanations welcome!

Thank you


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PostPosted: Thu May 07, 2020 4:32 pm 
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Joined: Sat Jun 30, 2018 11:46 am
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I've got it I think!

Fractions... 2/3 equivalent is 21/14
So for the 7/6 to work you would:
7x2=14
6x2 =12

So the ratio would be 12/21 simplified to 4/7

Thank you.


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PostPosted: Tue Jun 16, 2020 4:01 pm 
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Joined: Tue Nov 05, 2019 2:47 pm
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Yes.

edited by a moderator

LEARN: The trick with these questions is to scale the ratios so that the common link has the same value. This allows you to combine all the ratios into the form x:y:z.

ANS: We know:
M:A , A:I
3:2 , 7:6

The LCM (lowest common multiple) of 2,7 (the values of A in the ratios) is 14, so you want the A's to become 14. Do this by scaling (multiplying) each ratio by two constants (numbers).

M:A:I
21:14:12

M:I
21:12 which simplifies to 7:4 by diving by 3.

The answer is 7:4 as we require M:I, order is important in ratios.


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PostPosted: Thu Jun 18, 2020 6:19 am 
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Joined: Sat Jun 30, 2018 11:46 am
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Thank you Lucy Lu. Very helpful.


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