Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the average speed for ships before 1974 with over 1.73 passengers?

### Inputs:
table_name: table, columns: ['Ship name', 'Year', 'Length', 'Width', 'Passengers', 'Vessels', 'Speed']

### Response:
SELECT AVG Speed FROM table WHERE Year < 1974 AND Passengers > 1.73