Model 3 — Connecting the Ratios

04 Try it yourself Interactive

Scaling the bridge

Set two ratios that share a term. The walkthrough names the bridge, scales both ratios to the LCM of its two sizes, merges and simplifies, then does the same job again with neighbour fill and reads the two original pairs back out of the answer as a check.

A : B = 2 : 3 and B : C = 4 : 5

bridge scaled to 12 · 8 : 12 : 15

Try A : B = 3 : 4 with B : C = 8 : 9. The bridge sizes are 4 and 8, so the LCM is 8 and only the left ratio needs scaling — the neighbour-fill answer then needs dividing through, which the LCM route avoids.

Press Next to work through it one step at a time.

Bridge size–

A : B–

B : C–

A : B : C–

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