Ratio Word Problems — Full Lecture
Section: Word Problems · Bank code: WRD-RAT · GRE frequency: Medium-High · Class length: ~60 minPro
Thesis of the whole lesson: write every quantity as a multiple of k, then ask what stayed the same. The invariant is what turns a confusing story into a single equation.
How to use this capsule
Read straight through, it is a lecture script with timings. Sections are numbered in teaching order, and each opens with a time budget.
Three kinds of block appear throughout:
- Teaching note — what to say, what to ask, where to pause. Written for the teacher, but students self-studying should read them too: they name the mistake before you make it.
- Board — the one line worth writing on the whiteboard.
- Answers are hidden inside collapsible blocks so you can attempt first.
Running time: hook 3 · core & diagnosis 7 · machinery 13 · worked examples 15 · practice 4 · traps & tricks 7 · challenge 9 · close 2.
The rest of this note is part of Pro
Must-know rules, three worked examples, the GRE traps, speed tricks and a self-check — plus every one of the 75 concept notes and all 8,390 questions.
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