Exercise 03
The 40% Drop
Marketing is in a panic: "Signups fell ~50% last Tuesday (Jun 23). Real, or a tracking bug?" The product is US-only, users skew Pacific. The signups table stores signed_up_at_utc in UTC. PDT = UTC-7 for this date range.
Table: signups(id, signed_up_at_utc).
Show the daily signup count for Jun 21–26, **bucketed by Pacific local date** (`local_date`, `signups`), ordered by `local_date`. Confirm or refute the drop.