Predict: missing passenger counts in an average

Predict the two averages over the sample trips.

what to return

Columns: avg_knownavg_as_zero in this order
Rows: in the order asked
Watch for: Use only the sample rows shown. NULL is not zero or empty text. Keep duplicate rows.
Skill: Reason about the exact result of a fixed SQL query. Refresher: COUNT, SUM & AVG →

data you can query

Mobility dataset: the first 6 rows of each table. Under each column name: the kind of value it holds, and which table it links to. Your queries run on all rows.

trip_sample2 columns · 6 rows

trip_id	passenger_count
20	1
21	3
22	1
23	NULL
24	2
25	2

trip_id: 20
passenger_count: 1

trip_id: 21
passenger_count: 3

trip_id: 22
passenger_count: 1

trip_id: 23
passenger_count: NULL

trip_id: 24
passenger_count: 2

trip_id: 25
passenger_count: 2

all 6 rows

predict.sql

SELECT
  ROUND(AVG(passenger_count), 2) AS avg_known,
  ROUND(AVG(COALESCE(passenger_count, 0)), 2) AS avg_as_zero
FROM trip_sample

Read the query · predict its result

SELECT ROUND(AVG(passenger_count), 2) AS avg_known, ROUND(AVG(COALESCE(passenger_count, 0)), 2) AS avg_as_zero FROM trip_sample

Look at the sample tables and SQL. Enter the rows you think the query returns, in this column order: avg_known, avg_as_zero. Put each row in square brackets, then wrap all rows in another pair of brackets (JSON format). For example, [[1,null]] is one row with 2 values. Replace these with your predicted values. Use numbers without quotes, text in double quotes, and null for SQL NULL. Keep repeated rows. Use [] for no rows. Keep rows in the order specified by ORDER BY.

Your predicted rows

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Hints and the answer are always available. Using them counts the question as solved with help.