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Maths question help - ratio
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Author:  ciaowood [ Thu May 07, 2020 4:51 pm ]
Post subject:  Maths question help - ratio

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

Author:  ciaowood [ Thu May 07, 2020 5:32 pm ]
Post subject:  Re: Maths question help - ratio

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.

Author:  LucyLu75 [ Tue Jun 16, 2020 5:01 pm ]
Post subject:  Re: Maths question help - ratio

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.

Author:  ciaowood [ Thu Jun 18, 2020 7:19 am ]
Post subject:  Re: Maths question help - ratio

Thank you Lucy Lu. Very helpful.

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