Average Delivery Time for First-Time Buyers | Dataford Interview Questions

Given a table of user transactions and a table of delivery logs, write a query to identify the average delivery time for first-time buyers at Meta Logistics. Treat the earliest transaction for each user as their first purchase and include only transactions with a recorded delivery timestamp.

Output

Return one row with average_delivery_time_minutes.
Report the average elapsed time from the first transaction to delivery, in minutes, rounded to two decimal places.

Schema

user_transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
user_id	INT	Identifier of the purchasing user
transaction_at	TIMESTAMP	Timestamp when the transaction was placed
amount	NUMERIC(10,2)	Transaction amount

delivery_logs

Column	Type	Description
delivery_log_idPK	INT	Unique delivery log identifier
transaction_id	INT	Transaction associated with the delivery
delivered_at	TIMESTAMP	Timestamp when the delivery was completed

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