A hospital keeps a sealed container of radioactive waste in a shielded store until its activity is low enough for disposal.
The storage record is incomplete.
| Record entry | Value |
|---|---|
| activity when placed in the store | 7200 Bq7200\ \text{Bq}7200 Bq |
| half-life | 6 days6\ \text{days}6 days |
| time in the store | 18 days18\ \text{days}18 days |
| activity now | ______ |
Calculate the value that should be entered for the activity now.