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If a:b=3:2 and b:c=3:2, then a:b:c=?
9:6:4
9:4:6
6:3:4
6:4:3
9:6:4
To find a:b:c when a:b and b:c are given, align the common term b by taking the LCM of its two values (2 and 3, which is 6) and multiply both ratios accordingly.
a:b=3:2 and b:c=3:2
a:b:c=(a├Чb2тАЛ):(b1тАЛ├Чb2тАЛ):(b1тАЛ├Чc)
To find a:b:c when a:b and b:c are given, align the common term b by taking the LCM of its two values (2 and 3, which is 6) and multiply both ratios accordingly.
Students often directly combine the numbers as 3:2:2, forgetting that the middle term b must be equal in both ratios before combining.
Write the given ratios
We are given two ratios involving three variables a, b, and c: a:b=3:2 and b:c=3:2.
a:b=3:2,b:c=3:2
Equate the common term (b)
The value of b in the first ratio is 2, and in the second ratio, it is 3. To make b equal, find the LCM of 2 and 3, which is 6.
LCM(2,3)=6
Scale both ratios
Multiply the first ratio (3:2) by 3 to get 9:6, and multiply the second ratio (3:2) by 2 to get 6:4.
a:b=9:6,b:c=6:4
Combine into a single ratio
Combining both scaled ratios yields a:b:c=9:6:4.
a:b:c=9:6:4
A is correct because combining the ratios a:b=3:2 and b:c=3:2 by making the common term b equal results in 9:6:4.
Proportion and ratio-scaling techniques are frequently used in partnership problems, mixture and allegation, and physics numericals involving proportional quantities.