{"id":"fpa-unit-cost-bridge-lines","audience":"fpa","category":"finance-work","track":"finance","technique":"verification","level":"intermediate","title":"Bridge a unit cost increase by driver and check it ties","free":false,"task":"You're explaining why unit cost rose from Q2 to Q3. Write a prompt for plain text with lines starting \"Materials:\", \"Labor:\", \"Freight:\", \"Total change:\" and \"Tie-out:\". Show each driver as a signed dollar amount per unit, then the total change in dollars and percent of Q2. The tie-out line checks Q2 cost plus the change against Q3. Don't mention supplier rumors or next quarter. Under 80 words. No bullets or numbering.","materialLabel":"Unit cost drivers (attached to your prompt automatically)","material":"UNIT COST BRIDGE INPUTS - Starter Kit, per unit\n\nQ2 unit cost: $18.00\nQ3 unit cost: $19.20\n\nDrivers of change, Q3 vs Q2 (per unit):\n- Raw materials: +$0.80\n- Direct labor: +$0.50\n- Freight: -$0.10 (renegotiated carrier rate)\n\nOther comments in the file: a buyer heard from a supplier that resin prices may rise again next quarter, but there is no quote. Percent change is measured against Q2.\n\nBackground: the Q2 and Q3 unit costs come from the cost accounting system and include materials, direct labor and freight but not overhead. Q3 output was 38,000 units. The labor increase reflects the new union wage scale that took effect July 1. The carrier contract was renegotiated in August. The bridge is for the COO's staff meeting on Nov 12.","rules":[{"type":"plainText"},{"type":"maxWords","max":80},{"type":"maxBullets","max":0}],"promptHints":[{"label":"Names the five lines","patterns":["materials:","labor:","freight:","total change","tie-out"]},{"label":"Asks for signs and per-unit","patterns":["signed","per.unit"]},{"label":"Gives the percent base","patterns":["percent of q2","18\\.00"]},{"label":"Bans rumors","patterns":["(do not|don'?t).*(rumor|next quarter)"]},{"label":"Caps length","patterns":["\\d+\\s*words","plain"]}],"mistakes":[{"title":"Mentioning the resin rumor","why":"The AI adds that resin prices may rise next quarter.","fix":"Add: \"Do not mention supplier rumors or next quarter.\"","checks":["r2"]},{"title":"Freight shown as an increase","why":"The AI loses the minus sign on freight.","fix":"Say: \"Driver lines are signed per-unit amounts.\"","checks":["r0"]},{"title":"No tie-out","why":"The AI never checks the bridge reaches $19.20.","fix":"Add: \"Tie-out: Q2 plus the change equals Q3, with the numbers.\"","checks":["r2"]},{"title":"Markdown extras","why":"The AI adds bold labels, headings and a closing note.","fix":"Say: \"Plain text, no bold. Output only the lines asked for.\"","checks":["plainText","maxBullets","r1"]},{"title":"Trusting the AI to count words","why":"AI is bad at counting and runs past word limits.","fix":"Ask for fewer words than the real cap and keep each line short.","checks":["maxWords"]}],"hint":"A bridge has signed drivers, a total and a tie-out. Name the lines and ban speculation.","rubricLabels":["The lines starting \"Materials:\", \"Labor:\" and \"Freight:\" show +$0.80, +$0.50 and -$0.10 per unit","The line starting \"Total change:\" shows +$0.80 + $0.50 - $0.10 = +$1.20, which is 6.7% of $18.00","The line starting \"Tie-out:\" shows $18.00 + $1.20 = $19.20, matching Q3, and the output never mentions the supplier rumor or next quarter"]}