Forecast a project's final cost from spend and progress so far

Project: {{project_name}}
Total approved budget: {{budget}}
Who needs the forecast and why: {{audience_and_purpose}}
Known changes ahead (price rises, approved changes, extra work): {{known_changes}}

By work package or phase: budget, planned value to date (what we planned to have spent by now), actual cost to date, and percent complete with how it was measured:
"""
{{cost_data}}
"""

Task:
Forecast the final cost of the project from the figures above, for {{audience_and_purpose}}. I need to see whether we are spending faster than we are progressing, and what the final cost is likely to be if that continues.

Format:
1. Summary: two or three sentences giving the forecast final cost, the difference from budget, and whether the trend is improving or worsening, if the data shows it.
2. Table by work package with the columns Package, Budget, Earned value (budget × percent complete), Actual cost, Cost performance (earned value ÷ actual cost), Forecast at completion (budget ÷ cost performance).
3. Two forecasts for the whole project, with the arithmetic shown: (a) if the remaining work costs what was budgeted: actual cost + (budget - earned value); (b) if current cost performance continues: budget ÷ cost performance. One sentence each on what it assumes.
4. Schedule check: earned value against planned value, and what that says about progress.
5. Drivers: the packages causing most of the overrun or saving.
6. Known changes: added separately on top of the forecast, each with its source.

Requirements:
- Under 400 words, plus the table.
- Show every calculation so that a finance colleague can check it. Round money to whole units and ratios to two decimal places.
- Percent complete must reflect finished work. If the notes show it was estimated from spend or time elapsed, say the forecast is weaker, because measuring progress by spend makes every project look on budget.
- Use only the figures above.
- For a package with no cost or progress yet, cost performance cannot be calculated: forecast it at its budget and say so. If the package forecasts do not add up to forecast (b), explain the difference in one sentence.

A good forecast is one a finance colleague can check line by line and reach the same totals.

Example of one calculation's form only, with invented numbers: "Design: earned value $40,000 (50% of $80,000), actual $50,000, cost performance 0.80, forecast $100,000."

If a package is missing a figure, leave it out of the totals, say so, and show how the forecast would change if that package finished on budget.