Equilibrium P
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PLAY · INTERACTIVE
DRAG IT.
Three sandboxes. A supply-and-demand cutting mat, a CPI heatmap, and a real Edexcel multiple-choice question. Try the first one with no account — answer it and you'll see the explanation.
Supply & demand · cutting mat
FIG. 01 · ELASTICITY · 1.2Demand shift+0
A rightward shift simulates rising income, preference, or population.
Elasticity |E|1.00
A flatter curve responds more to price. Necessities sit near 0.4; luxuries above 1.5.
Equilibrium Q
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The market clears where the marginal buyer's willingness equals the marginal seller's cost. Both sides are negotiating, even when no one is in the room.
CPI · component heatmap
FIG. 02 · INFLATION · 2.6UK CPI · APR 2024 → APR 2025 · ANNUAL CHANGE · ILLUSTRATIVE
Housing & energy
+7.2%
Food & drink
+3.4%
Transport
+2.9%
Restaurants & hotels
+4.1%
Health
+2.2%
Education
+5.1%
Recreation
+3.8%
Communication
+1.7%
Headline CPI lands at ~3.5%, but only because housing & energy is hot and dragging the rest with it. Strip those out and the BoE's "core" measure looks much closer to target — which is why monetary policy sometimes responds to one number and sometimes to another.
One question, no account.
FIG. 03 · LIVE Q · 1.5.3EXTRACT · UK SUGAR LEVY (2018)
The UK's Soft Drinks Industry Levy ("Sugar Tax") took effect in April 2018: 18p/litre on drinks with 5–8g sugar per 100ml, 24p/litre above 8g. Many large brands reformulated to avoid the higher band. Sugary-drink consumption fell roughly 10% in the first two years; obesity rates have continued to rise.
Which of the following best describes the Sugar Tax in welfare-economic terms?
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