Branches With Above-Average Water Flow

SQLMediumMid level~15 min

Problem

A municipal water utility records every metered flow between water meters. Each meter belongs to one branch office, identified by an area code embedded in the meter records.

Write a query that returns the branches whose **average flow per logged transfer is strictly greater than the global average flow per transfer** across the whole network. A meter participates in a transfer whether it is the source or the target of the flow.

Return one column named `region` (the branch city). Order does not matter.

Tables

Example rows — the live problem includes the full dataset.

branch

branch_id	city	area_code
1	Riverside	RV
2	Hilltop	HT
3	Lakeview	LV

meter

meter_id	branch_id
10	1
11	1
20	2

flow_log

source_meter	target_meter	litres
10	30	33
20	30	4
10	20	59

Expected output

Your answer should return 2 rows with the columns region.

Starter code (SQL)

SELECT *
FROM branch;

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