{"id":"fpa-plan-gross-margin-hosting-cost-table","audience":"fpa","category":"finance-work","track":"finance","technique":"format","level":"intermediate","title":"Show gross margin by plan with the corrected hosting cost","free":false,"task":"You're comparing plan profitability for the product lead. Write a prompt for a markdown table with columns Plan, Customers, Margin per customer, Margin % and Monthly margin, with the math in the last column like \"500 x $21 = $10,500\", followed by a last line starting \"Blended:\" showing total monthly margin divided by total monthly revenue as a whole percent. Use the invoice-based hosting costs. Margin per customer is price minus hosting cost; Margin % is margin per customer divided by price. Under 130 words.","materialLabel":"Source material (attached to your prompt automatically)","material":"PLAN ECONOMICS - monthly, October 2026\n\nPlan | Customers | Price per month | Hosting cost per customer per month\nBasic | 500 | $30 | $9\nPro | 200 | $80 | $32\nTeam | 50 | $300 | $150 (dashboard estimate)\n\nFinance note, Nov 3: the hosting provider's invoices show that Team plan customers cost $180 per customer per month, not the $150 on the dashboard. The Basic and Pro costs agree to invoices.\n\nNotes: only hosting is included; support and payment fees are excluded here. The product lead will use the table in the Nov 12 pricing review.","rules":[{"type":"maxWords","max":130}],"promptHints":[{"label":"Names the columns","patterns":["plan","customers","margin per customer","monthly margin"]},{"label":"Uses the invoice cost","patterns":["invoice","180","correct"]},{"label":"Defines blended","patterns":["blended","total monthly margin","total monthly revenue"]},{"label":"Asks for the math","patterns":["show","x"]},{"label":"Caps length","patterns":["\\d+\\s*words","under \\d+"]}],"mistakes":[{"title":"Using the dashboard cost","why":"The AI keeps $150 for Team and gets 50%.","fix":"Say: \"Use the invoice-based cost: Team is $180.\"","checks":["r1"]},{"title":"Missing the multiplication","why":"The AI shows monthly margin without the math.","fix":"Add: \"Show customers x margin per customer.\"","checks":["r0"]},{"title":"Wrong blended math","why":"The AI averages the three percentages.","fix":"Add: \"Blended = total margin / total revenue.\"","checks":["r2"]},{"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 part short.","checks":["maxWords"]}],"hint":"Pick the cost that agrees to invoices, show the multiplication, and define the blended line.","rubricLabels":["The table has columns Plan, Customers, Margin per customer, Margin % and Monthly margin and shows Basic $21, 70%, 500 x $21 = $10,500 and Pro $48, 60%, 200 x $48 = $9,600","Team uses the invoice cost: $300 - $180 = $120, 40%, 50 x $120 = $6,000 (not $150 and 50%)","The last line is \"Blended:\" showing $26,100 / $46,000 = 57%"]}