Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_46 ( guests INTEGER, ship_name VARCHAR, year_built VARCHAR )

### Question ###
What is the number of guests for the Viking Ingvar, built earlier than 1990?

### Accurate SQL ###

SELECT AVG(guests) FROM table_name_46 WHERE ship_name = "viking ingvar" AND year_built < 1990