add basic excel challenge

challenges/basic-excel-challenge/2025Q2_ExcelTest.xlsx:Zone.Identifier

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+[ZoneTransfer]
+ZoneId=3
+HostUrl=https://files.slack.com/files-pri/T6DN889HD-F08P7KVBCH1/download/2025q2_exceltest.xlsx?origin_team=T6DN889HD

challenges/basic-excel-challenge/README.md

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+# Basic Excel Challenge
+
+A basic excel challenge that tests some skills that would be expected for someone to have basic analyst role. A data-team grade data analyst should fly through this. A Domain Analyst is expected to be able to complete it in the proposed timeline, with possible minor mistakes.
+
+## Goals
+
+The challenge requires the candidate to put to use the following skills:
+
+- Be able to read existing tables and understand what's in them.
+- Perform filters on a clean table.
+- Perform % of total calculations.
+- Compute mean and mode statistics of a series.
+- Create line charts.
+- Perform single key and composite key joins across tables.
+- Import CSV files into Excel.
+- Run basic arithmetic formulas.
+
+Some of these can be solved manually, through formulas, with pivot tables, etc. It's possible that different candidates use different strategies.
+
+Besides this, you can emphasize more or less the importance of pretty result presentation, reproducibility, methodology explanations, etc. That's up to you and not really defined in the test.
+
+## Inventory
+
+- `basic_excel_challenge - starting file.xlsx`: the workbook that serves as both starting point and instructions for the challenge. Candidate can use a copy of it as his working area.
+- `rates.csv`: a supplementary file that the candidate will have to import into the workboox.
+
+## How to use
+
+- Provide the candidate with both `basic_excel_challenge - starting file.xlsx` and `rates.csv`.
+- Sprinkle any specific instructions you might want to add.
+- Send it all to the candidate, provide a timeline and sit tight.
+
+## Solutions
+
+We still haven't done them lol. If you do it, please add to the repo.