Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_27011761_2 (train_no VARCHAR, departure VARCHAR)
### Question:
How many trains depart at 17:30?
### Answer:
SELECT COUNT(train_no) FROM table_27011761_2 WHERE departure = "17:30"