You're analyzing data from a study on penguins and need to divide them into three equally sized groups based on their body mass. Write an SQL query that selects the species, island, and body_mass_g for each penguin from the little_penguins table. Additionally, add a new column named body_mass_class that assigns each penguin to one of three groups (terciles) based on their body_mass_g, with the lightest penguins in group 1 and the heaviest in group 3.
Use SQLite syntax to write your answer. Descriptions of tables are provided in the right pane.
Write your request in the field below and click the "Check it!" button.