Final answer:
An informal writing style can be used for a report when it addresses controversial topics, is short and routine, or addresses complex information.
Step-by-step explanation:
An informal writing style can be used for a report in the following situations:
- When the report addresses controversial topics, as an informal style can make the information more accessible and engaging to readers.
- When the report is short and routine, as an informal style can make the content more concise and straightforward.
- When the report addresses complex information, as an informal style can break down the complexity and make it easier for readers to understand.