The Detective’s DeskMeri Cole
Proposed deduction
“The combined average is 5.25 kg.”
MEDIUM · CASE FILE
A misleading average
Medium · MEADOW PARCEL DEPOT
Two batches of sealed parcels have certified average masses. Four porters calculated the average for the combined batch. Also reconstruct the review register: it records who examined which source, independently of whether their later proposed answer is correct. Review slots describe order, not travel or clock times.
Read the case file below, or open the interactive desk to examine records, keep notes and submit your reasoning. These are the case materials, without the solution.
Your assignment
Whose combined average is correct?
- The analytical records answer the analytical question; worksheet records establish the review reconstruction. Candidate proposals and supplementary recollections are claims to test.
- There are 2 ordered events. Use each listed person and item once in its column. “A immediately before B” means A is in the row directly above B, with no row between them.
- 4 verified records support the complete submission. Keep the separate context note out of the proof.
- No outside facts or unstated exceptions are required. The complete board and report are assessed together.
People and accounts
Nico Ward
Proposed deduction
“The combined average is 9 kg.”
Oona Lake
Proposed deduction
“The combined average is 4.5 kg.”
Luca Ash
Proposed deduction
“The combined average is 6 kg.”
Case records
Read each record on its own terms. A claim made by a person is different from a fact established by an independent record.
PRIMARY RECORD
Small batch certificate
Two parcels have a total mass of 6 kg, so this batch averages 3 kg per parcel.
This gives both the size and mass of the first batch.
LINKED RECORD
Large batch certificate
Four more parcels have a total mass of 30 kg, averaging 7.5 kg per parcel. Combine all six parcels.
This gives the second batch and the combined parcel count.
CONTEXT NOTE
Wrapping record
All six parcels use brown paper and blue string.
Their wrapping does not establish a mass or average.
RECONSTRUCTION RECORD
Review register
This is the same investigation’s document review record. There are 2 ordered events, labelled Review 1, Review 2. Each listed person and item occurs exactly once. These slots describe record order, not times from the analytical problem.
- The event reviewed by Nico Ward occupies slot 2 (Review 2).
Use each column’s choices exactly once. Verified relationships govern the board; proposed answers and later recollections do not override them.
RECONSTRUCTION RECORD
Review cross-check
The relationships below were verified independently. “A immediately before B” means A is in the row directly above B, with no row between them. Keep relationships from all worksheet sources together.
- The event involving “Small batch certificate” occupies slot 1 (Review 1).
Use each column’s choices exactly once. Verified relationships govern the board; proposed answers and later recollections do not override them.
Questions to resolve
Match every recorded item to its handler or reviewer.
- Small batch certificate
- Large batch certificate
When was the primary analytical record reviewed?
Use the interactive case desk to select your finding and cite the records that support it. The answer is checked there, and your progress stays in your browser.
Build your finding
Compare the records with each account. Work out what the evidence establishes, then separate that finding from anything it does not prove.