A large, open-top cylindrical tank is filled with an ideal fluid to a constant height. A small hole is drilled in the side of the tank at a depth d below the surface of the fluid, and the fluid exits the hole with a speed v1. The first hole is then sealed, and a second small hole is drilled at a depth 4d below the surface of the fluid, resulting in an exit speed v2. What is the ratio v2/v1 of the exit speeds?